/sqt/ - Stupid Questions Thread | QTDDTOT

>>8571619
No prior physics.

Lots of prior math.

Is it possible for me to swap uni's during the bachelor years?
If not, would it be possible for me to do my masters in a different uni after I've finished my bachelor in one uni?

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kinda starting to get it

wouldnt mind a bit of clarity though

>>8571637
>Is it possible for me to swap uni's during the bachelor years?
yes

>If not, would it be possible for me to do my masters in a different uni after I've finished my bachelor in one uni?
this is also possible

>>8571636

Would there exist a list of mathematical topics anywhere?

>>8571641
what are you even asking? 2 obviously isnt less than 1

what does 'set of upper bounds of empty set in X' even mean?

why can i cum twice in like 5 minutes?

does the body really start remaking semen that quickly or does the body willfully not ejaculate all that you have stored up?

someone in the last thread posted refractary period but that seems more about orgasm than ejaculation

[math]\sum_{n=0}^\infty \frac{x^n}{n!} = e^x[/math]
How would I say this?
I just finished Calc2 and I understand what it means but I couldn't actually say this in regular speech

>>8571695
lefthandside is the taylor expansion of e^x

>>8571696
Yes, I understand that, but how would I say that?
Like if I wanted somebody else to write out this equation what would I tell them

>>8571695

Word for word: the sum from n=0 to infinity of x to the n over n factorial

Or what >>8571696 said.

>>8571699
'sum from n equals 0 to infinity of x to the n over n factorial equals e to the x'

>>8571699
the sum where the summing index n goes from 0 to infinity of x to the n-th power divided by n factorial equals e to the x?

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>>8571619
Is this any good ? I like when I read it, I do a few problems here and there but it seems rather light on the maths.

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>>8571707
>>8571709
bueno

>>8571619
linear algebra, differential equations, integral calculus, basic chemistry knowledge, and during the course you'll learn about operators and other things like that which are important for understanding QM.

>>8571637
yes

>>8571695
The sum, for n going from 0 to infinity, of x to the power of n divided by (I also say "on") n factorial.

>>8571713
introductory physics is light on math, dont worry.

>>8571647
That guys retarded. You need to know classical mechanics, electrodynamics, complex analysis, and algebra to learn graduate level quantum mechanics.

>>8571619
So I got cheated in my grad algebra class and never learned about modules.

Is their anything significant I'm missing that wouldn't be covered in the theory of vector spaces? I understand ideals can be thought of as modules, which makes module theory appealing for talking about ideals and vector spaces at the same time.

Any books you guys would recommend to get me up to speed?

>>8571651
>set of upper bounds of empty set in X
an example of a set of upper bound of a subset Y in a set X
X={1,2,3,4,5,6} Y={1,2}
the set of upper bounds of Y in X is {2,3,4,5,6}
as clearly these elements are all larger than or equal to all elements of Y

the least of all of these upper bounds (often called the supremum) is 2


now repeat with Y= empty set and X={1,2}

>>8571885
then trivially the set of upper bounds of the empty set is X and the set of lower bounds is also X

What are some good books on the history of geology? Most of what I find are textbooks but would like a better narrative. I like books that reflect on man's early scientific attempts to explain the earth and that cover major events, people, and their ideas.

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I have a bit of prior experience with proofs and I would like to improve, do you guys think it's a good idea to go through Linear Algebra Done Right in order to improve?
I don't know almost anything linear algebra besides some computational sutff with matrices

>>8571791

how'd you cheat?

>>8571892
now back to >>8571641
comparing the least of all upper bounds, and the largest lower bound

there is no contradiction for non-empty subsets

>>8571921
there's no contradiction for empty sets either

>>8571923
so is the problem notation?

or is 2 less than or equal to 1

>>8571932
where do you get 2 less than or equal to 1 from?

>>8571934
transitivity of the binary relation

im guessing the problem is notation

>>8571943
why does transitivity give you it? can you explain clearly why youre getting 2<= 1?

>>8571943
the empty set isnt a number so you cant say 2<= empty set and empty set <= 1

>>8571950
i think it is common notation to compare an element and a (sub)set in such a way

only this notation isnt necessarily the same as the binary operation

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why does the stress decrease at the necking section of this graph? surely as the area decreases the stress should increase? Am i missing something basic

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>>8571619
I'm pretty stupid but I want to do something STEM. My college only offers civil and electrical engineering. I'm more interested in electrical engineering. What should I start studying to prepare myself? I'm a freshman btw.

Pic mildly related: I'm autistic enough to play this piece of shit game so maybe i'm autistic enough to actually learn something useful instead.

>>8572036
Stop thinking that "being enthusiastic about something" is equivalent to autism, it will only hamper your advancements in whichever field of study you want to take.

>>8572034
That's an engineering stress-strain plot where everything is measured relative to original dimensions. If you were to look at a true stress-strain plot, the plot would be always increasing.

>>8572036
either watch some ocw lectures or make a project that interests you, something like a simple programming project or soldering project will be rather helpful.

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>>8572053
It's just 4chan terminology, anon. Anyways, how much of a role does inherent potential have? How true is it that anyone is capable as long as they're willing to study/apply themselves? I've gone my entire life being told that, but I'm curious as to how true it actually is. I don't want to waste time and money attempting something that I lack the intellectual capacity for.

>>8571967
it doesnt sound very common or logical

you can compare elements to elements or sets to sets but not elements to sets

Can anyone recommend a good C IDE that runs on Windows 10?

>>8571619
QM is very math intensive. You will need at least up to 2nd year math and 3rd year physics to make a good stab at it. If you want; I could make a list of rough topics that will help greatly to prepare you for it.

I have a stupid question, /sci/:
I have a few meshes that I want to calculate / simulate a few things on. I have been looking without much success for a program that can calculate principal axes of rotation (at least) and preferably simulate a rotating body
Also, I need a program that can simulate a falling body with enough fluid dynamics or mimicry of fluid dynamics to simulate wind resistance. I'd been looking at a few solvers that I'm not sure have these capabilities but don't really want to commit to anything shitty and have to start over again.

Does anyone know of any software that can do these things?

>>8572053

being obsessed with arbitrary and non immediately real object is autism anon, high end math people are anomalies and equating them to autism is fair.

>>8571619
Textbooks/books to start studying physics?

Also what are you reading in your downtime /sci/?

>>8571637
Yes both of these are possible and if you are thinking of going to a more prestigious university I would wait until grad school as undergrad uni does not matter too much for grad applications as long as you get good recs and do well

Is it necessary to take Linear Algebra for EE? My uni doesn't require it but I've seen others do. Im done with all other required math classes and can just take it as a technical elective to count towards my major still

>>8571905
Someone help please

>>8571619

is oxygen plant poop

>>8572544

Did I win the thread yet?

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If a patient with Crohn's Disease became infected with HIV/AIDS, would that have the effect of mitigating their Crohn's Disease?

>>8572241
> Using an IDE for C

>>8572579
>Yep. Come at me.

>>8571619
To really begin understanding quantum theory, you need a good background in the Hamiltonian formulation of classical mechanics, including canonical variables, Poisson algebras, Hamilton Jacobi theory, etc.

You also need a very good background in linear algebra, since the quantization of quantum mechanics involves mapping classical variables and functions (like canonical variables and Hamiltonians) to linear operators on complex vector spaces.

Some Fourier analysis couldn't hurt either.

What is the practical use of moles and molarity? I don't even remember what the latter is. It's been almost a decade since I took chemistry and I need to know some basics.

>>8572643
Easy way to work with quantities in terms of number of atoms/molecules

>>8572142
a binary relation ~ on a set is just a subset of the set's cartesian product with itself

comparing two elements is just checking if their ordered pair is in this subset ~

then comparing an element with a subset X would just be checking if all relevant ordered pairs are a subset of the binary relation ~

an example is finding the largest and smallest element of the whole set, using the whole set as the subset X

>>8572669
>then comparing an element with a subset X would just be checking if all relevant ordered pairs are a subset of the binary relation ~
and there are no relevant ordered pairs when X is empty, because theres nothing to compare to

>>8572707
and the empty set(no relevant pairs) is a subset of ~

this comparison is weaker than a binary relation

>>8572792
idk man you seem confused about what you're even trying to accomplish, i'd recommend not comparing elements to sets

>>8571619
I maintain that my first quarter of quantum mechanics was the absolute hardest class I ever took in university. (Chemical engineer, top 10 public university in the usa)

I'd recommend that you've completed calculus in entirety (differential, integral, multivariate, probably vector), ordinary differential equations, one semester of classical mechanics (intro physics), up to a year of general chemistry, and possibly a semester of programming depending on your university.

If all you seek is a conceptual understanding, wikipedia and other online sources are surprisingly thorough for a lay men's take.

>>8572796
its useful shorthand

particularly for bounds of non-empty subsets

>>8572807
you probably shouldnt use <= then

2 <= empty set <= 1

reads like 'every x in the empty set satisfies 2<=x <=1' which is of course true but this doesnt imply 2<=1 since youre using nonstandard notation

How do I learn multiplication?

>>8572838
Flashcards are probably your best bet (for up to, say 12*12). After you know the basic multiplication table on the back of your hand, learn how to do long multiplication. Then it's just a matter of doing a shit ton of calculations while learning other things (algebra, probably, or geometry) until you gain fluency.

Stupid question.

What kind of advances in technology in all sectors can I expect in 2017?

How to layout resume as sophomore looking for engineering internship?

>>8573145
You may want to try complete sentences and proper grammar, firstly.

>>8573145

be sure to include how many dicks you've sucked. experience counts at the higher levels

>>8573125

virtual waifu and fuck-tech.

>>8573167
How to try to complete sentences and proper grammar?

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Ok, so we all know that the universe is continuously expanding faster and faster, but in a way that the distance between any two particles grows at the same speed.

But what if the universe is not actually expanding, but everything inside of it is just getting continuously smaller?

I'm going into my 3rd year of a physics major. I seem to be able to do physics problems, but I don't think I really understand the physics. I get the math (or am able to perform calculations at least) but I don't think I really have a physical intuition to look at the world and at nature and see how things work and how they are related and so on and so forth.

How do I remedy this?

do insects feel pain?

>>8573573

Unless you're Richard Feynman, developing a "physical intuition" will only prohibitively slow you and cause you to struggle to pick up new crazy theories anyway.

Just keep going with the math. Most of the pop science fans who spout all the "le no-one understands quantum mechanics XD" memes are doing it because they're trying to build some sort of intuitive mental model with rock solid discrete billiard balls that bounce of each other instead of just relying on the mathematics.

Modern physics is too abstract for physical intuition, we say "shut up and calculate" for a reason.

>>8572838
visualize (or draw) a number on the number line. if you multiply it by 2, it gets 2 times as far away from zero. try different numbers and multiply them with different numbers to see the relation.

>>8571619

Is there any sense in which one construction of the reals is "better" than the other?

In my real analysis course, they're using Dedekind cuts. Is there value in learning how they construct them other ways, or is learning it just this one way for my first time through real analysis fine?

>>8573125
the first commercial payment cards with flexible fingerprint scanners on them

>>8573643
I'd say learning multiple ways of constructing [math]\mathbb{R}[/math] is useful for mathematical maturity. There's a way that uses the set [math}QC,[/math] which is the set of all Cauchy sequences whose elements are all in [math]\mathbb{Q}.[/math] If you decide to learn both, your mathematical maturity will go up.

>>8571791
atiyah-macdonald

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>>8571619
Ok, really stupid question. What does my picture mean?

I know about sums but that is not the usual notation and while d and N are both natural numbers (in this context), I have reasons to believe that this does not just denote the sum from d to N of some expression.

>>8571748
>implying quantum mechanics is graduate level
Fucking lel

>>8573941
sum of every divisor d of N

i.e if N=6 then you sum over 1,2,3,6

>>8573947
Oh, that makes sense. Thank you.

>>8573943
It can be... my uni has graduate level QM. However, OP is most likely referring to undergrad level.

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Is I-section beam symmetrical or unsymmetrical?

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What's the specific term for the sectioned part of the circle highlighted in red?

>>8574581
circular segment

http://abcnews.go.com/Technology/story?id=120095


is this real

>>8574645
no

http://www.askamathematician.com/2010/10/q-in-the-nec-faster-than-light-experiment-did-they-really-make-something-go-faster-than-light/

and it's pissing me off that it says "july 19" implying it's from 2016 but it's actually from 2000

>>8572036
How did you get started with Dwarf Fortress?

How does one prove that if x^2+y^2 is even then x+y is even?
It seems to be self-evident (from the property of addition and multiplication of even numbers), but I have no idea how to construct a proper proof because I'm an idiot.

>>8571619
i just finished a bachelor's in mechanical engineernig.

i'm unsatisfied with my education, and I want to learn more about math and physics (modern physics and engineering mechanics).

what books do you guys suggest I study?

>>8571619

I just had some 3d data that I represented with a 2d plot of colored data

what happens if we take 4d geometry and represent it as 3d colored data

I guess the problem then could be that data could interesect (multiple points with same x,y,z) but for some data maybe these interesections would not ruin it completely

>>8575113

x has the same parity as x^2 (x = x^2 mod 2)
y has the same parity as y^2 (y= y^2 mod 2)

so x^2+y^2 being even means both x^2 and y^2 have the same parity (x^2 = y^2 mod 2)

so x and y have the same parity (x= y mod 2)

so x+y is even

>>8575141
Thanks, fellow stranger

High school education here, didn't take 'precalc' or study math seriously at all.
Where/how do I get gud at just reading even the symbols used for math beyond x=3+y? I know some of the names but I picked up a random higher level book (calculus with analytic geometry) and was completely baffled seeing the first page. literally where does one start with this whole field?

>>8575115

after I get my EE degree I will get a comfy EE job and buy some nice lab equipment and start working on projects

you can really do absolutely anything you want. You have the capacity to become any of the old obscure science dudes you hear about on this channel

https://www.youtube.com/channel/UCtwKon9qMt5YLVgQt1tvJKg

Do something like this:

https://www.youtube.com/watch?v=41r3kKm_FME
(he's laying out the pcb for a slowmo camera he designed himself)
https://www.youtube.com/watch?v=JbCM3f0ofW4
https://www.youtube.com/watch?v=VdjYVF4a6iU

start a simple website where you post descriptions/pictures of your projects

>>8575153

Thanks anon. It would be cool to have a youtube channel/ website where I document my projects.

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>>8571619
Is this proof correct?

>>8575115

Taylor & Wheeler - Spacetime Physics
Kolecki/NASA - Foundations of Tensor Analysis for Students of Physics and Engineering With an Introduction to the Theory of Relativity (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050175884.pdf)
Rindler - Introduction to Special Relativity

Taylor - Classical Mechanics
Corben & Stehle - Classical Mechanics (Dover Books)
Fetter & Walecka - Theoretical Mechanics of Particles and Continua (Dover Books), Nonlinear Mechanics: A Supplement to Theoretical Mechanics of Particles and Continua (Dover Books)

Eisberg & Resnick - Quantum Physics of Atoms, Molecules, Solids, Nuclei, and Particles
Schumacher & Westmoreland - Quantum Processes, Systems, and Information
Bohm - Quantum Theory (Dover Books)

Hammack - Book of Proof (http://www.people.vcu.edu/~rhammack/BookOfProof/)
Shilov - Linear Algebra (Dover Books), Elementary Real and Complex Analysis (Dover Books)
Kreyszig - Introductory Functional Analysis with Applications

>>8571713
That's what freshman physics is. The book assumes you're learning calculus at the same time so it starts off lite.

>>8572449

You really should take at least one course on it. If your area in EE uses LA at a lot then you should consider doing 2 or 3 classes on Linear Algebra.

>>8572241
>coding in C
>in 2017

Just use C++17

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The set defined by pic related would be {0, 2, 4, 6} right? Afaik, if the universal quantifier at the start wasn't there the set would still be the same? What does a universal quantifier in a situation like this do?

>>8575367
looks like its either {0,2,4,6} or {2,4,6} depending on whether you consider 0 natural

im nots ure why the universal quant is there or what the dot is

>>8575376
Well the dot (blob) means replacement, and 0 is considered natural.

I have only ever see a quantifier in a position like that when the question asks me of the predicate is true or false, never when I'm asked to give the set defined by one.

''Two complex numbers are equal if and only if their real parts and imaginary parts are equal.''
Can someone prove me that?

>>8575513
if a=b then a-b=0
|a-b|^2=re(a-b)^2+im(a-b)^2 = 0

>>8575513
That comes directly from the construction of the complex field as ordered pairs.

>>8575245
bumping for answer to this.

>>8571662
Scrotum stores more sperm than 1 ejaculation
>>8572554
Not in the first year or so, and not if hiv infection is controlled, if aids breaks out then yes likely
>>8573578
Yes they notice e.g. that something is wrong or something is biting them or that they are missing a leg. They certainly feel hunger or too hot temperatures (burn). But they dont feel pain or hurt as much as e.g. we humans do. However it is still partially unknown atm.

>>8575520
If you are going to take this approach which will run into a logic wall somewhere you have neglected to show that if ||a-b||=0 then a=b.

>>8575113
Alternative approach:
(x+y)^2 = x^2+2xy+y^2
=> x^2+y^2=(x+y)^2-2xy
2xy is always even, so x^2+y^2 has the same parity as (x+y)^2 which has the same parity as x+y.

>>8575536
>Scrotum stores more sperm than 1 ejaculation
does the 1st ejected load somehow contain the 'strongest' sperm?

>>8571619
>How much prior physics do you need to start in on studying quantum mechanics

To start, freshman physics.

>>8575657
1st has much more spermatocytes per milliliter. You could call it 'stronger' but it makes you sound a bit retarded.

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How do I solve this? I've read the theory but it just goes over my head. Anyone have examples of this type of problem being solved?

i get around 8 hours of sleep but always get sleepy after half an hour or so of studying

what do

>>8575679
>he does sperm cardio instead of getting spermatozoa gains

>>8575937
What is the atomic make up of a modern computer? Just the memory and CPU
Is a motherboard or a circuit board needed, would direct wires be enough?
How does a well programed CPU process input information, how is this thing structured?

>>8571619
Which topics from abstract algebra are absolutely necessary for graduate level linear algebra?

Are REUs difficult? I'm thinking of applying for some and all of them mention a presentation or whatever. I really do not like public speaking but are these presentations difficult at all? Also, do the professors help you out or just throw you in because I don't know what the fuck some of them are about but they sound neat.

>>8572241
atom with linter and gcc compiling packages. you will need MinGW, though.

https://leangsimschoolboy.files.wordpress.com/2013/09/student_solutions_manual_for_mathematical_methods_for_physics_and_engineering.pdf

For exercise 3.13 on page 58 of this pdf, what is going on at the top of page 59? Where is the intuition for this meant to come from?

>>8573423
you can model the change the same way either way, the best way to explain a continuous shrinkage of mass is a continuous expansion of the universe around the mass. As far as we know particles cant just change size and retain the same amount of mass, so an expanding universe is the more logical answer

I read that it is accepted that energy is a thing that particles have and particles are not 'made of' energy and are their own thing, what is the problem/inconsistently with the idea that particles are an expression (don't know if that's the right word) of energy interacting in different ways?

>>8574308
there would be no reason to make it unsymmetrical since that would create a relative weakness in the beam. As long as the cross sectional area is the same on both sides the very center can be paper thin as long as the flanges are strong enough to take the normal forces from loads (and of course as long as there are no transverse shear forces through the center of the beam)

>>8576035

You're really just altering the meaning of the word, as used in physics, to be what you'd like it to be. Energy is a property of physical objects (matter, waves, particles, fields, etc.). Energy is also not physical by itself--only changes in energy. Often you set some convenient zero and can deal with particles with zero energy.

A good comparison that isn't overly contrived isn't coming to mind (i.e. something kinda goofy like mileage is a property of cars, all cars have it, but cars aren't physical manifestations of mileage acting in strange ways) but the real issue is that such a statement doesn't really have a place in scientific discussions of physics. There's probably no inconsistency since it doesn't really translate to anything other than attaching a belief system to a scientific concept. Energy is energy and particles have it. Un-particles on the other hand...

>>8576104
So then are particles 'things' that are all one single 'thing' that has changing properties dependant on the energy it has, like when say a muon and an anti-muon collide and become two photons they are still the thing that is a particle but the properties are different (change in mass, loss of mass, change of charge etc) is that right? Or am i trying to simplify something complex too much?

What's the best way to learn a programming language such as C# on your own?

>>8575245
i don't quite understand it

>>8575776
stay hydrated

>>8576161
learn the basics from books/websites

make your own programs, starting with simple exercises and moving on to harder and harder programs until you're making "real" programs

you'll learn things as you go along and as you read about things that you get stuck on or you want to learn more about

Best Uni for Physics undergrad?
Princeton, Yale, Stanford, Dartmouth (free tuition with finaid)
Georgia Tech (would be making around 3,000 a year with scholarships and finaid)

>>8571641
In the definition of upper and lower bounds of sets of real numbers, there is a requirement the sets be nonempty to avoid this.

>>8571905
It might be a bit hard, but it should be doable if you understand proofs well.

>>8573643
As long as you come away with a field in which Cauchy sequences are closed it doesn't matter how you do it. You can look for other constructions for shits and giggles.

>>8571905

Linear Algebra Done Wrong might be better for you.

>>8575152
khan academy is your friend

>>8576324
>shits and giggles
found the urban redneck

>>8576343
>let me insert my irrelevant white hatred here
found the SJWtard

>>8576297
Go to Georgia Tech if it is cheapest/ they are paying you because undergrad does not matter enough to spend money on

>>8574785
Hmm. I'm pretty sure I just watched youtube videos by Captainduck. He makes tutorials for it every few years I think, and once I got the basics I just figured it out on my own. It's not actually a hard game, it's just kind of complex at first because there's so many small details and the UI is horribly unweldy.

Guessed I'd come here for some advice from my fellow /sci/entists. Any of you has a good intro to topology book to recommend? That stuff looks fun. Also, what are the requirements if you want to understand topology? My math level is not the highest so I'm kinda worried I won't understand a thing.

>>8576316
ive seen at least one textbook use the convention that the supremum of empty set is -infinity and infimum is +infinity

>>8576666
That is correct, but that is a convention used to make it so that the infimum of the empty set is always bigger or equal to the infimum of any other set and its supremum always smaller. If it weren't that way, the empty set would mess everything up since it is a subset of any set.

This still doesn't imply that you can compare elements to sets.

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Retarded Physics Undergrad here.
So I have this question on a worksheet which involves gravitational force and potential below the surface of the Earth. Everywhere I've looked, people chose to just define the new potential by the "inner sphere", with a radius of [math]r-h[/math]. This results in

[math]g=g_0*(1-h/r)[/math].

I can see how that works if [math]r>>h[/math].
For greater dephts, however, I would figure that I would have to solve this geometrically, factoring in the masses of both sphere segments as opposed forces (pic related)
Is everyone over-simplifying, or is it just me being retarded?

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>>8576643
In theory you don't need anything other than the ability to handle abstraction in order to do basic topology. That said, in my opinion your first topological concepts should be in the setting of real analysis (there's a chapter in Rudin about metric spaces and topology).
Without the bare bones of analysis examples to look back to I think you'll find yourself getting stuck with "why are they doing this?" moments over and over.

But if you've had a babby analysis course take a look at this. The length is very nice for just exploring a little bit rather than going through a systematic doorstop (it's about 160 pages I think).

>>8576686
I'm not 100% if this is what you're asking but when you are inside a sphere (technically a ball), only the sphere of your current radius matters in terms of gravitational force. You can actually prove that the gravitational forces from the portion of the sphere from r (the outer surface) to r - h (current radius) cancel.

>>8576686
>>8576724
Here's a link. http://hyperphysics.phy-astr.gsu.edu/hbase/Mechanics/sphshell2.html

The proof comes from that the gravitational force inside a spherical shell is 0 everywhere. The layer from r - h to r can be thought of as h shells that contribute nothing to the force.

>>8576728
Yeah, thanks, that's what i meant.

I see a lot of anti-evolution arguments that go along these lines.
1. Species exists.
2. Said species has certain features that make it suited to survive in its particular environment.
3. Evolution of these features must have taken millions of years.
4. Thus, this species survived in the same environment millions of years ago without those particular features, because they hadn't evolved yet.
5. If it was surviving fine without those features, why did those features evolve in the first place? Evolution debunked.

How do I argue against this?

>>8571641
The LUBP property says EVERY NONEMPTY SET OF REAL NUMBERS HAS A LEAST UPPER BOUND.

What is an UPPER BOUND for a set S in the reals?
An upper bound for S is an element x in R such that FOR ALL s in S, s =< x.

The reason we avoid THE EMPTY SET in this definition is because any statement that begins "FOR ALL X IN THE EMPTY SET" is automatically true because there are no X in the empty set to verify the statement for!

I'll bite.

Are the Bogdanoffs legit or word salad?

>>8575977
Nice dubs.

Binge some computerphile vids on jewtube, they are very good

>>8576316
>>8577299
dont worry, this has nothing to do with real numbers

the motivation came from babby set theory

and the mistake found in abusing notation, thanks to >>8572829 and other anons

>>8577287
>4. Thus, this species survived in the same environment millions of years ago without those particular features, because they hadn't evolved yet.
that's the wrong assumption. they all died.

>>8577287
Environments change gradually with space and time, thus Species van gradually evolve over either one of these dimensions. Further changes May cause the environment to become an island, giving the illusion of An abrupt change.

>>8575295

Anon, thank you very much

>>8575513
z1 = a + ib
z2 = a' + ib'

z1 = z2. So z1 - z2 = 0

z1 - z2 = (a - a') + i(b - b')

If a =! a' or b =! b', then we have z1 - z2 = c + id

So a = a' and b = b'.

>>8575113
Both anons were correct. However, a more useful method for proofs would be to say :

x^2 + y^2 even => x + y even is equivalent to :
x + y uneven => x^2 + y^2 uneven.

The second proposition is much easier to prove.

>>8577299
what is the least upper bound of R?

>>8575735
take the derivative with respect to each x_i. set these equal to zero. that's (a). solve for the minimizing values of the x_i.

It's not really any different from what you learned in calculus.

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Hypothetically, as a graduate student can I keep IP that I develop on my own time?

>>8576271
Definition: two systems of linear equations are equivalent if each equation
in each system is a linear combination of the equations in the other system.

Because the system is homogeneous all of the equations are equal to 0 and for this system to be equivalent to the second system all the equations of it much be a linear combination of the other system. So my thinking is I must find a c_1 and c_2 such that the linear combination of the second system is equal to all of the equations in the first system, c_1 = 0 and c_2 = 0 works.

Failed engineering and so I decided to take some business classes. I have no motivation to even go to class and class starts Wednesday. What can I do to do the whole "fake it until you make it" thing?

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Two weeks for my math exam (mix out of Calc II + Calc III).
I just watched the lecture videos. I know the 'If you can't do the homework then you can't do the exam'-phrase.

But what's the best approach to get the best out of this situation and and learn as much as possible? Just practising the shit out of everything? What's the best tactic to learn 16 weeks of coursework in a clever way?

>I just bought 15 cans of energy-drinks and willing to make sacrifices to every god there is.

Any math majors want to explain why they love math and why they find it fascinating? I've been pondering this question for a while now as I'm very interested in physics but have never had an appreciation for math.

I really want to like it but it seems like most people I ask just respond with "I've always been good at it so that's what I majored in". I'm hoping to see the beauty of math for myself but with a little bit of exposition from one of you who deeply understand and love the subject.

Thank you in advance

does Fregean 'sense' refer to the sign exclusively or also the qualities implied by the sign.
So "the morning star" and "the evening star" have different senses, does this mean that they contain the words "morning" vs "evening" or also that they are the star visible in the morning vs evening

>>8577287
>3. Evolution of these features must have taken millions of years.
first of all "feature" is not a scientific word so it doesn't refer to anything specific. secondly assuming you mean something like "legs that are very good at jumping", features don't slowly develop for millions of years and then begin to work suddenly like a computer program. they work from the beginning in increments, and because they give those individuals within a species a survival/reproductive advantage over others in their species, they die out less quickly/reproduce more prolifically, causing that species to "evolve" in the direction of "jumping good". This may also be propagated by a counter-evolution, like fast tongues of their predators. so the frogs are licking faster and the bugs are jumping faster until the frogs have bullet tongues and the grasshoppers are teleportation. I'm joking of course, but that's the reason bugs fly so fast, and birds see so well.
>4. Thus, this species survived in the same environment millions of years ago without those particular features, because they hadn't evolved yet.
again, it doesn't work like loading, evolution is either gradual or punctuated by things like bottleneck and founder effects.

>>8571695
I feel like this nigga is lying. You've somehow managed to pass calc 2 and don't even know how to pronounce that in English? Who was your professor? Was his name bob jones? Did he have Down's syndrome?

Any way to get my hands on papers without paying? I feel like there is no such thing as piracy for /sci/ papers, or that I have to look harder.

What's the maximum speed an average human (dead or alive, it's only the mass that's important) could reach in an absolute vacuum?

>>8577955
behold:

http://sci-hub.bz/

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PROVIDE A BIJECTION FROM (0, 1) TO [0, 1]

CHECK IT

0 TO 0.1 TO 0.11 TO 0.111...

1 TO 0.8 TO 0.88 TO 0.888...

>>8577974
thats from [0,1] to (0,1), and you only specified where countably many of the points are mapped to

>>8577977
Obviously everything else = itself

>>8577974
Okay? So? If you show me that (0,1) and [0,1] are homeomorphic, I'll care.

>>8577974
This is better

{rt^k(2) - 1 = rt^(k+1)(2) - 1 where k = natural
{rt^m(2) - 2 = |rt^(m+1)(2) - 2| where m = natural
{else = itself

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>>8577987
It's an exercise from before the derivation even you fucking retard. It doesn't have to be "continuous".

>>8577844
>I get very angry when I'm wrong in front of people.
I spend a lot of time proving stuff carefully so I don't ever have to be wrong when I present my math.
>I don't like doing more than one thing in a day.
Math lends itself to obsession.
>I like creating detailed pictures in my head.
A mathematical object is only understood in so far as it's a picture in someone's head. When a field starts advancing beyond the mental pictures, it starts stagnating. Good graduate professor will insist you not only have a proof, but a picture to make the proof superfluous. This appealed to me a lot.

Sort of related: I also really like reading literature with lots of detailed descriptions, but I can get bored with novels that are straight dialogue.

>>8577998
>from before the derivation even
I don't know what this means.

I'm just pointing out that you're posting something trivial and acting (via your reaction image) like it's something interesting. It's embarrassing and annoying.

>>8577999
>A mathematical object is only understood in so far as it's a picture in someone's head.

That's a point I can understand. I had one very enthusiastic teacher who used triceps muscles to explain cubic functions. I think it takes true creativity to be able to attach the abstractions to something tangible and that is of course the best way to see the beauty of math for most people. Unfortunately I only had 1 semester with that professor so since then I've been fed nothing but formulas and equations with no context correlating them.

You said math lends itself to obsession, but what about it exactly makes you obsessed? I'm just interested to know where this fervor comes from

I'm a 20 years old NEET who has never studied anything seriously and practically wasted most of my life watching anime. I want to know everything about math and quantum physics before killing myself. Where is the best place to start? What are the most appropriate books and how should I practice?

>>8578003
I thought you were denying it's validity like that faggot with a BSCT proof picture. Interestingness is relative to your knowledge.

>>8578012
>what about it exactly makes you obsessed?
How available the full experience is. I sit down and read a textbook and I'm doing math. I conjure up a question that can be understood in mathematical terms and I'm doing math. No other STEM field is like that. To get the full engineering experience, you have to build things. To get the full science experience, you have to have a lab to test things. The full math experience is available all the time.

But also:
>hating to be wrong in front of people
>fearing I'm insignificant

>>8578065
>To get the full science experience, you have to have a lab to test things. The full math experience is available all the time

Wow that's pretty true actually, never thought about it like that before. I love physics and chemistry but until you get into a lab it's literally all just somebody's ideas that you're memorizing, the real learning comes from application. However, math is entirely theoretical and can be learned, explored and applied entirely with a book, a sheet of paper and a pen.

I'm still trying to get excited about the subject itself but that way of thinking definitely makes it seem less boring than reading a chem textbook.

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WTF give some hints.

Does it have something to do with the properties of relatively prime numbers?

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I really didn't want to create a thread for this, as I consider it to be very off topic. But I hope I'll have some answers here.

I am looking to find a partner interested in several things such as learning and investigating, writing, etc.

One could say some sort of ''accountability'' or partnership.

I guess this thread is already an attempt at trying to find somebody. But, if its badly perceived by the people around here, perhaps you could advice me as to where I could go to find somebody (besides real life...)?

>>8578161
Investigating what? Crimes? You fucking autist.

>>8578165

Mmm? Why so hostile, anon?

>>8578169
Because I hate myself and I'm projecting.

>>8578172

>Investigating what?

Many things, whats within reach, whats agreed onto. Its a difficult question to answer, anon.

>>8577995
Wrong. Try being less of a fucking moron next time.

>>8578161
sure. how do I contact you

>>8578221
[email protected]

>>8578224
nice. do you have a pager?

>>8578221

I forgot to mention something very important.

Its complicated anon. My level aint that high on any fields you could name. I am afraid I would be wasting my partners time if he were to be on a complete different league than me.

I just wanted to clarify that.

>>8578235
do you have an email?

>>8578238

[email protected]

>>8578241
Sent ;)

Drop-out from highschool(GED) and college here, recently been thinking about going back and maybe getting into a science field(neuroscience or physics seem interesting). My problem is I am math retarded and my education took a huge hit in high school when I dropped out. The reason for dropping out, to tldr it, was that I was a glitch/ghost in the system and would've been forced to retake my year/s there since NONE of my stuff was ever recorded.

Anyway, digressing, should I hire a tutor to essentially teach me math and what else I missed out on from dropping out and then attempting to head into those fields, or am I fucked and should just give up right now?

>>8578251
Do you have a job? The likelihood of you finding a job in these fields is basically nonexistant, just like how I am too short to be a basketball player. You can study as a hobby though

>>8578253
I don't have a job but luck seems to keep throwing money at me. So it isn't worthwhile to even attempt to study aside from being a hobbyist? Is the reason finding a job basically nonexistant correlated with my shit educational past?

>>8578257
>Is the reason finding a job basically nonexistant correlated with my shit educational past?
You just have to realize that with fields like physics and neuroscience it takes your whole life of everything going smoothly and then some to break out and really do something. I dont know much about neuroscience but you arent getting a job as a physicist anywhere without undergraduate studies and then a PhD, thats about 10 years of effort and hundreds of thousands of dollars in expenses. and you will be competing with people with far greater natural abilities, greater work ethic, and probably everything already good on the other side of things. I suggest you think really hard about what you actually want and if its worth what you must sacrifice

>>8578264
Alright, I thank you for your answer and honesty.

>>8578264
Wew you sound like a faggot. I bet you wasted a good part of your life as a social slave instead of actually using your brain processing power to do something meaningful. Just let people learn whatever they want and create their own interpretation of the world. How many genius do we need to waste before we realize capitalism fucked up science..

>>8576327
>>8576320
Right now I'm giving it a try, thanks you guys

>>8578275
"meaningful" is subjective. in the real world putting food on the table is more important

This is so late in the thread no one is going to answer, but in case you do, here's my question:
How do people know how many digits a constant is accurate to? By that, I mean how are we sure that pi never goes up to 3.14160? Pi just being a quick example.

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>>8578302
Copy-pasting my answer from another thread :
From a physics point of view :
I'm sure if I understand well, but I've always been taught that if you do an operation with 2 values of different precision, you need to crop the number of significant digits to the one of the least precise term.

Ex : 0.5 + 0.987 = 1.4 because 0.5 could as well be 0.512 but you've only got 0.5

However : 0.500 + 0.987 = 1.487

I was also told not to round to the nearest integer, but to crop entirely. If you're really serious about it, you can use a standard incertitude value by taking the precision of your measure (ex, if your ruler has 1 mm precision it's 1*10^-3 m), dividing by sqrt(3) (because it's the confidence interval of a Gaussian repartition) and multiplying by 2 (because since the values might be distributed following a uniform distribution, you need to enlarge your incertitude to the maximum)

So for 0.5 + 0.987. 0.5 is precise to +/- 0.05, 0.987 is precise to +/- 0.005

0.5 + 0.987 = 1.4 is precise to +/- 0.055. The standard incertitude is 0.55*(sqrt(3)/2)

0.5 + 0.987 = 1.4 (+/- 0.063)

There's also a much more convoluted and complicated formula for getting the incertitudes of combined expressions, but that's mostly for physicists and (serious) engineers.

That's the practise
Now for the theory, pi was evaluated by Archimedes as the perimeter of circle of radius 0.5.

Archimedes and the Greeks knew how to accurately measure the perimeter of any polygon. They also knew that the circle was a polygon with an infinity of sides. So they draw a square inside and outside the circle, and evaluated pi. Then they drew an octagon, and so on...

>>8578318
Okay, thanks.

I had an MRI done to my head and the results say "cortical subcortical atrophy", how fucked am I?

>>8578275
>capitalism fucked up science
lolno, quite the opposite. and there are governmental and other grants to fund actual good research regardless of how profitable it is

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im supposed to get a definite answer for this integral but i don't know how to proceed further than this. what do?

>>8578335
(4*5 - 5^2) - (4*2 - 2^2) = -9

>>8571716
>knows how to write the Latex command for the sum but can't translate it to English

You're some special kind of stupid, my friend.

>>8578337
what did you do??

>>8578339
https://en.wikipedia.org/wiki/Integral#Calculating_integrals

>>8578335
Try splitting the sums and integrals.

>>8578323
you can post here? seems to me you are alright

>>8578340
But how do you do that with riemann sums?

>>8577287
>that make it suited to survive
that would be better expressed as
>that help him to survive better

>species survived in the same environment millions of years ago without those particular features
not as good as with

>If it was surviving fine without those features
it was not. it was cold, frightened, and hungry.

>>8578351
i'm not sure what you're trying to do i just did the non-handwritten part

>>8578345
Maybe on the surface, but I'm worried it's going to devolve into some sort of mental breakdown from all the shit that's going on underneath.

>>8578355
M8....

>>8578358
As long as you're able to commit suicide you're fine.

>>8578364
???

>>8578367
Funny you mention that. I've been there, the reason being I consider myself worthless scum that should be put down, and every time I pull back with the same excuse: I'm too valuable. That's not logical, and if I go batshit I'll be even less logical about it and be unable to put myself down when I start hurting others. So I wanna know now if I should off myself right away or if this is something that can be dealt with.

>>8578358
>it's going to devolve into some sort of mental breakdown
that's not going to happen
you might experience cognition or memory problems

>>8578381
I don't know what kind of artificially complicated life you have but first you should stop hurting yourself.

>>8578388
Thanks for the advice but I'm not a cutter or anything like that, I treat my body very well. My mind not so much.
>>8578385
Thanks for your input too, I'll continue consulting my specialist.

>>8578247
kek

taking "mathematics for scientists" in a couple of weeks

any tips?

molecular biology major

>>8578598
take a calculator with you

>>8578610
we're not supposed to used them

but thanks anyway

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hey /sci/, got a trig question for you.
In the picture there, the gun is being rotated from the shoulder along with the rest of the arm. How do I get the gun to rotate to follow the crosshair if the point of of rotation is not the center of the gun.

>>8572034
Might have something to do with work hardening.

>>8578856
elaborate?

>>8578917
I would like the gun to rotate so that it is always pointing at the crosshair. The point of rotation of the gun is shoulder(the red dot). How do I get the gun and the shoulder to rotate so that the gun is always point at the crosshair?

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Consider hexagonal close packed spheres, i want to describe the path between the spheres in a way such the path is always equally far from the neighboring spheres. Webm related.

I slapped together a script that generates such a curve, but i suck at math to put it into a curve function.

Basically there should be some parameter t.
x = t
y = triangleWave(t) * yScaling <- this here is a problem
z = sin(t*pi) * zScaling

My problem is i need a function with parameter t generate this curve, also this curve must be differentiable. The triangle wavy part makes this impossible, also it just looks bad if you look at it on the last frames of the webm.

Can anyone help me out with this? Or point me to the direction?

>>8578941
>equally far from the neighboring spheres

im not entirely sure what this means, which spheres in particular

can this be differentiable at the points shown at 0:06?

>>8571748
>classical mechanics, electrodynamics
What for?

To build some intuition why framework of classical science fails? Sure.
But you don't need it to be able to solve QM problems.

Relativity is needed, however at first you start with non relative QM.

as >>8571636 stated, mainly math.


>>8572063
Depends on how good is the university at given field. You can easily go through the same degree at some universities and feel like the dumbest person in the world in others.

Inherent potential is key if you want to go for the high end jobs, university etc. But even if you're not as STEM intelligent, you could do well enough in a poor university or one of the easier/less math intensive STEM degrees.

>anyone is capable as long as they're willing to study/apply themselves? I've gone my entire life being told that, but I'm curious as to how true it actually is.

Has no basis in reality. HOWEVER, trying hard is a key to success. If you're not working hard you're not going to make it no matter how smart you are (unless daddy gave you a load of money, won the lottery etc).

>>8577611
I wrote this as an explanation of my reasoning. It's probably wrong and why I'm posting here. Someone answer my question pls

how do I solve the following without a calculator and hours of my time:

13x^2-6x-99=0

usually I times the first and last coeffiecent together and then find two factors that also add to make the second coeffiecient.

>>8578960
Try to move a point through hcp spheres such way that it always stay equally far from the closest spheres. Does that help to imagine?

>can this be differentiable at the points shown at 0:06?
The x and z coordinates can be but not the y because the triangle wave peaks are discontinuous. This is why i feel this is not the best solution for this.

>>8579046
13 is prime, so you know your factored form is going to be
(13x- )(x- )
with some stuff. Then it's a matter of filling in the stuff in the correct way.
You can guess that the number in the x bracket must be small, since it's multiplied by 13 while the other isn't, but the difference is only six. +-1 obviously won't work so the next smallest one to try is three, which does.

>>8571619
Does dark matter's "dark" property have anything to do with the speed of light? Like, is it possibly vibrating faster than light or something? That would explain why it's "dark"

>>8579068
Possibly, but probably not. It's hard to answer virtually any question, even ones thought to be physically impossible, in the form "is dark matter X?" because nobody has much of a good idea what dark matter actually _is_. The reason it's named dark is just because it doesn't interact with light; why is an open question.

>>8571619
How much scientific credence does the "stoned ape theory" have? I've heard a few people mention that evolutionary it makes sense, but mostly because of the way it improves vision systems.

>>8579071
Interesting. So the reason it's dark is because it doesn't interact with light, but we know that it is similar to regular matter? Couldn't it just be regular matter that happens to move faster than light, thus light cannot escape from it?

>>8579079
It's really not very similar to regular matter. It can't just be regular matter moving faster than light, because it's impossible for regular matter to do that (and this is a point physics is fairly certain about). Not to mention that in order for an FTL object to be invisible it'd have to be coming towards you; that's not the case.

It's stuff with some very weird properties (it interacts with gravity but seems to be completely immune to electromagnetic interactions) so it seems reasonable to guess it's not made of electrons and protons (which are charged) but beyond that it gets difficult.

Why humans can't breed with other species?

>>8579097
Actually I recently heard that things like "humanzees" may be possible. Short answer is moral reasons. Technically though there should be no reason why a human sperm and genetically similar ape egg couldn't combine.

In fact humans have interbred in the past. Neanderthal DNA is in a large amount of modern humans, and there is some research that suggests other members of the homo genus had the same phenomenon occur.

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How does one solve these?

Like for the first one I know I have to take the integral over that interval, but how do I solve it?

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>>8579192
z table you probability pleb

in a ring, if ab is inversible, can you say that a and b are inversible ?

I already that if a and b are inversible, then ab is inversible

>>8579331
nope

(hint: look for counterexamples in rings that arent fields)

>>8579337
Thanks, i thought about polynomials, Z and D but didn't find any counter example !

>>8577603
publish it independently and have someone steal your idea that way :)

IP it yourself with smeckles or ...

>>8579347
my mistake, they are invertible

one line proof too

>>8572294
Solidworks can do that and it's pretty easy to use. Also NX can do that I think.
Have you tried ANSYS apdl?

>>8575981
>graduate level linear algebra

Depends, graduate level linear algebra could be anything from Numerical Linear Algebra to Matrix Groups.

>>8578933
rotate(currentPoint - rotationPoint, currentOrientation - crosshairOrientation)

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GRE practice question (not taking it just doing for fun)

What am I missing here? I have no clue how to proceed.

>>8579860
is it -2?

>>8579860
differentiate both sides: g(x)=15x^4

>>8579860
Differentiate to get g(t), then just solve 3x^5 + 96 = G(x) -G(c) ?

>>8579192
Don't you have a table with the data of the normal distribution?

>>8579869
>>8579871
yes indeed, thank you, it was in a bizarre form which confused me. Answer -2

When we differentiate, I assume we're doing so w.r.t. x? As such, the dt in the integral was confusing me a bit I think, I wasn't sure that we could take derivative with respect to x and still have the integral cancel out?

>>8579046
quadratic formula

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Next GRE one--I know the answer has to be A, but my method seems awful and inelegant.

The derivative is clearly 1+x+x2+x3...

Thus f'(0)=1. This eliminates {D,E}
Thus f'(-.5)>0. This eliminates {B}
And furthermore, via...harmonic or oscillation stuff? f'(-.5)>.5. This eliminates {C}.

is there 4 dimensional light

>>8579946
just once i i thought i wouldn't create an entirely new thread for my stupid fucking question and this is the thanks i get? crickets? had i made a new thread, i'd have 20 replies by now.
fuck you you stupid scientists. i'll make sure my tax dollars go toward clean coal subsidies in the future.

>>8579934
f'(x)= sum_{n=1}^infinity x^(n-1) = 1/(1-x) (geometric series)

>>8579934
If you have that [math] Df(x) = \sum_{n=0}^{\infty} x^n [/math], then for [math] x \in (-1,1) [/math] you have that $Df(x)$ is the geometric series and hence [math] Df(x) = \frac{1}{1-x} [/math].

Can someone explain group representation for a layman?
I'm reading wiki but the definition just flies over my head.
https://en.wikipedia.org/wiki/Group_representation

So, you have a vector field V and a group G, then you have:
p: G -> GL(V)
Such that
p(gh) = p(g)p(h) for all g, h in G

What exactly is GL(V)? What exactly is p? Is p just a set of linear transformation?

f(x) = u(x)^n
F(x) = (u(x)^(n+1))/(n+1)

Right ?

>>8580374
And doesn't matter what is u(x) right ?

>>8580374
>>8580385
no
not if you're integrating with respect to x

I can't think of a single non-polynomial function this works for

>>8580308
a group representation p is just a homomorphism of a group you're interested in into a matrix group

V is a vector space not vector field, GL(V) is the group of invertible linear transformations on V (think invertible matrices)

> Is p just a set of linear transformation?
yes it's a set of linear transformations, one for each g in your group G

you do this because you can get information about your group G very easily by using linear algebraic facts about the matrices you can obtain in representations

>>8580390
ok thanks, and primitive of cos(u) isn't sin(u), right ?
For u a polynomial function

>>8580421
i think i find it, primitive of cos u = (sin u) / u'
with u a polynomial function

>>8580427
more than a polynomial function, a function ax with a real

>>8579891
>I assume we're doing so w.r.t. x?
Yeah, check out the fundamental theorem of calculus [eqn]\frac{\text{d}}{\text{d}x}\int^x_cf(t)\text{d}t=f(x)[/eqn] for variable [math]x[/math] and constant [math]c[/math]

>>8579968
Why dont you open a thread for that then? Maybe its a smart question thread worthy question and its been wrong here all along anyway.

>>8575776
And try a small coffee

>>8576025
Post screenshots plz

>>8579946
What does that mean

>>8572034
Because newtons 3rd law. it's accelerating rapidly as it necks.

>>8571619
I feel like I'm being retarded:
3/8 students in a class have brown hair
1/2 of those students (with brown hair) have brown eyes
What fraction of students in the class have both brown hair and eyes?
I swear I'm doing a degree in physics but I don't know why this has stumped me

>>8577964
If accelaration is equal for all atoms in the body, theiretically 99% of c or something like that.

How feasible would 1984's techniques of torture and brain washing be for -- say -- prisoner rehabilitation?

How feasible would they actually be in a world as described in the book, and would they actually be worth the effort in order to eradicate any form of martyrdom and unorthodox thought?

>>8579078
Not much. As a byproduct. But not mainly taken into account.

>>8579097
If the chromosomes dont match no mitosis is possible. Even if an ape sperm would enter a human oocyte, that thing resulting would decay.

>>8575152
precalc will introduce the concept of functions and sums and all the symbols you don't know. plus graphing all the garbage you learned in algebra but never had anything to apply it to.

its really easy you should just do it on khan and then do some practice tests to make sure you know it. you can blow through pre-calc and cal 1 in like a month or two if you give it a solid daily effort.

>>8579104
Neander and human are the same species man they intermix as easily as blacks and asians. The main reason is imcompatibility and not moral. Apes and humans cannot mix technically-biologically.

>>8580497
Its more metaphorical.

>>8580528
I wasn't aware this was /lit/. Where could I get an actual answer to my questions?

I'm preparing for my graph theory exam and there's one thing I don't quite get.

Given some arbitrary graph G, find all pairwise non-isomorphic graphs that we can get by adding exactly one new edge.

I am aware of the fact I can somehow use non-trivial automorphisms (axis symmetry, rotations). But the only way I can see is simply adding one arbitrary edge, then applying all combinations of automorphism to see the projections. However this approach seems quite messy and not systematic.

Is there a better system?

>>8580534
On /lit/.

What's more impressive, a PhD in physics or a PhD in math?

How do you do log4(x)-10logx(4)=3?

I'm confused about whether to reduce it to a quadratic or just solve it as is?

>>8580720
>log4(x)-10logx(4)=3
log4(x)-10/log4(x)=3
y-10/y=3
y^2-10-3y=0
(y+2)(y-5)=0 by visual inspection
>y=5
log4(x)=5
4^5=x=1024
>y=-2
log4(x)=-2
x=4^-2=1/16

>>8580728

Thanks for that, forgot about substituting log4(x) for y.

>>8577995

PLEASE CHECK ILL SUCK UR DICKER

>>8580706
math

>>8571619
You need a college E+M class but that's about it. Some calculus too.

im prepping for next semester. should i focus on linear algebra or electricity and magnetism?

How many notes do you have usually have per class?

I just counted mine for this semester (3/4 over) and I got about 116 pages written. Some examples, some explainations here and there. Feels kinda confusing now when I look at them.

I did organic chemistry back in 2015 and got A's. I have a big test that will have a lot of organic chem in a few months. I've forgotten quite a bit of it so I will start revising/relearning it. Is 2 weeks enough time to 'relearn' it or should I allocate more time?

>>8579658
Thanks!
Could you tell me how you figured it out?

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>>8581668
rotation transforms rotate around the origin, so you subtract the point of rotation to make it the origin, rotate, and then add the point back in

>>8581686
Why is that?

WHY can't the IS elements of composite transposons such as Tn10 transpose independently? Every site says the IS elements in composite transposons can't move independently but then Wikipedia says the IS elements of Tn10 actually can.
I don't fucking get it

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I´ve been having trouble with this problem for a couple of days and I cant see what I am doin wrong. For a) I have:
[math] r=\frac{30-3l}{2 \pi}[/math]

for b) I have [math]\frac{l^2(\sqrt(3) \pi -9)-180l+900}{4 \pi}[/math]

Then for c I have got the derivative of that as:

[math]\frac{dS}{dl}=\frac{l(\sqrt(3) \pi -9)-90}{2 \pi}[/math]

But where do I go from here? It seems I have gone wrong somewhere but I dont know where.

I hope my latex typing went right first time poster, thanks in advance.

>>8582012
fucked up my brackets its meant to be l(sqrt(3)pi-9) etc,

can we reduce this:

(e^x(sqrt(x)-1))/ (2 sqrt(x) *x)

i think not

>>8571619
I'm a ChE graduate who should probably refresh his mind on some of the key concepts since I've got some assessment centres with technical interviews coming up, but I don't particularly want to read through 4 years of notes.

Do any of you guys know of a decent 'refresher' book that just goes over the basics of reactor design, distillation columns, fluid mechanics, heat transfer, thermodynamics, all that stuff? I've got no interest in the calculations aspect, just the theory.

In principle, is it impossible to create a bicycle which is steered by rotating a gyroscope in order that the gyroscopic precession turns the bicycle?
I know (or at least think I know) the answer is no, as there is an absence of external forces, so linear momentum must be conserved. Fair enough, but why is that? From the videos of people sitting on spinning chairs and turning spinning bicycle wheels to cause them to rotate it just intuitively looks like it would be possible.

>>8573125
WEED

>>8573423
redshift in far away galaxies

Why do my freezer's temperature go up when the room temperature is freezing, and go back down to normal when it's typical room temperature?

File: 20170105_230343.jpg (3MB, 1896x2532px) Image search: [Google]

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Retard question.
How the fuck do I figured out which way the vector is supposed to be pointing? It's possible to draw different triangles with its components, which then gives different angles.

Thanks faggots. Would suck you off. N-n-no homo.

>>8582544
Why would the situation be any different for a gyroscope-based "autopilot" compared to a rider?

>>8582872
> It's possible to draw different triangles with its components
No it isn't.