/sqt/ - Stupid Questions Thread

>>8976643
>Have fun being baited by the resident sperglord wannabe mathematician who is unaware of his mental handicap edition
Just keeping things in check, wouldn't want to spread faulty proofs around would we?

>>8976643
>child with autism area
isn't this just all of /sci/?

>>8976643
Also I'm glad you approve of my formatting for /sqt/ OP posts.

>>8976643
Eat my shit, piggot

>>8976643
>t. brainlet who can't prove that floor(x-1)=floor(x)-1

"Thre metelly retartafd wil be aur footoo". - Mentally retarded kid

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>>8976841
it immediately follows from the definition of the floor function

below is the explanation for retards, you literally cannot refute it with any semblance of credibility

n is an integer (such as -1)

(x + n) mod 1 = (x mod 1) + (n mod 1) = x mod 1

frac(x) = x - floor(x) = x mod 1

floor(x) = x - frac(x)

floor(x + n) = x + n - frac(x + n) = x + n - frac(x) = floor(x) + n

>>8976846
>(x + n) mod 1 = (x mod 1) + (n mod 1) = x mod 1
to be extra clear,
(x + n) mod 1 = ((x mod 1) + (n mod 1)) mod 1 = x mod 1

>>8976846
That image does not have the definition of the floor function, but one of its properties.
The definition of the floor function is [math] \lfloor x \rfloor = \text{max}\{m\in\mathbb{Z}\mid m\leq x\} [/math].
Modulo 1 arithmetic is entirely redundant in your post. By definition [math] \mathbb{R} \ni x \text{mod} 1 = x - \lfloor x \rfloor = \{ x \} [/math]
>x + n - frac(x + n) = x + n - frac(x)
You did not prove this.

>>8976879
AHAHAHAHAHAHAHA KILL YOURSELF FUCKING RETARD

KILL YOURSELF

>>x + n - frac(x + n) = x + n - frac(x)
>You did not prove this.
YES I DID, NOT THAT I NEEDED TO BECAUSE IT'S GLARINGLY OBVIOUS, BUT:
>(x + n) mod 1 = (x mod 1) + (n mod 1) = x mod 1
>frac(x) = x - floor(x) = x mod 1
frac(x) = x mod 1 = (x + n) mod 1 = frac(x + n)

KILL YOURSELF KILL YOURSELF KILL YOURSELF

>>8976879
To be extra clear
>>8976846
>(x + n) mod 1 = (x mod 1) + (n mod 1) = x mod 1
You did not prove this.

>>8976884
You're a brainlet. Stay mad.

HEY GUYS PROVE 2+2=4 WHILE YOU'RE AT IT

I'D TELL YOU TO SUCK MY DICK BUT I'M NOT A FUCKING FAGGOT LIKE YOU ARE

>in chemistry
>cyclohexene
>breathes in fumes
Am i dying /sci/?

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Holy shit this is hilarious. The brainlet is fuming.
This >>8976774 is still the best proof.

>>8976884
You've yet to prove [math] \lfloor x + n \rfloor = \lfloor x \rfloor +\ n \ ,\ \forall \ n\in\mathbb{Z} [/math].
Moron.

>>8976902
you've yet to prove that you are worth the air you breathe

>>8976902
In case you don't get it:
[math] (x+n)\ \text{mod} \ 1 = x+n - \lfloor x+n \rfloor [/math]
You did not prove that you can remove [math] n [/math] from under the floor function.

>>8976904
Stay mad, fucking lolcow. What a retard.

>>8976905
you're a fucking joke

even the gorillaposter admitted that the mod 1 thing is trivial

>>8976908
The modulo 1 arithmetic is entirely redundant. You did not prove this >>8976902
You assume it as a definition like an imbecile. It's a property of the floor function, and you need to prove it.

>>8976915
>you need to prove it
jesus christ lmao

any integer is divisible by 1, n mod 1 is zero, it's obvious if you know what the floor function and the mod operator is, there is nothing to prove

>>8976919
>any integer is divisible by 1, n mod 1 is zer
Doesn't matter, you moron. We're talking about real numbers.
By definition [math] \mathbb{R} \ni x \ \text{mod} \ 1 = x - \lfloor x \rfloor [/math]
You've yet to prove that [math] (x + n) \ \text{mod} \ 1 = x \ \text{mod} \ 1 \ ,\ \forall n\in\mathbb{Z} [/math].

>>8976926
Or entirely equivalently >>8976902

>>8976926
n is an integer you insufferable retard

learn to read

it holds for n=-1 which was the original task

nice strawman argument faglord

why are you even replying? is your twisted sperg mind getting enjoyment out of it you sick fuck? enjoy your mental masturbation, enjoy deluding yourself into incorrectly thinking you won an internet argument.

>>8976930
Holy shit, you really need everything spelled out to you? What happened to chanting >muh obvious?
[math] (x+n) \ \text{mod} \ 1 = x+n - \lfloor x+n\rfloor [/math]
To prove that the above expression simplifies to [math] x \ \text{mod} \ 1 [/math] you need to prove that [math] \lfloor x+n \rfloor = \lfloor x \rfloor + n [/math]. Which is exactly what you're trying to prove. You're walking in circles like a retard.

>>8976938
that's a really shitty strawman argument. i never claimed (x + n) mod 1 = x + n - floor(x + n)

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>>8976941
Then you're an even bigger moron than I initially thought since that's how mod 1 arithmetic is defined for the real numbers.

>>8976945
>that's how mod 1 arithmetic is defined for the real numbers
so why are you claiming that i need to prove it?

If this is still a stupid questions thread...

Use the relation [math]\frac{1}{a^2-x^2}=\frac{1}{2a}(\frac{1}{a+x}+\frac{1}{a-x})[/math] to find the nth derivative of [math]\frac{1}{a^2-x^2}[/math]

I know that the solution is [math]\frac{n!}{2a}(\frac{1}{(a-x)^{n+1}}+\frac{(-1)^n}{(a+x)^{n+1}})[/math] however I have no idea how it's found. Any help would be much appriciated.

>>8976946
Are you somehow functionally illiterate too, not just mathematically illiterate? You don't need to prove the definition, but one of the properties of mod 1 arithmetic (or equivalently, one of the properties of the floor function).

>>8976953
Please reformat that.

Also why does my latex not work?

>>8976954
why would i need to "prove" something so basic? the fractional part of x is the same as the fractional part of (x + n) where n is an integer. it's completely fucking obvious.

>>8976958
Prove it if it's so obvious.

>>8976959
demanding that someone prove that (x + n) mod 1 = x mod 1 is like demanding that someone prove 2 + 2 = 4. it's infantile child play to get (You)s.

>>8976961
B r a i n l e t.

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"resistivity can be seen as the resistance of a 1m side cube"

resistivity = (resistance x area) divided by current

I don't get how that definition fits in with the formula. definition sounds like it should be "resistivity = resistance divided by volume"

also I don't understand why the unit is the ohm meter. How do you get that from (ohm x metre^2) divided by amp


can someone explain? I know what current is I've got a bit of a grasp on resistance.


I'm honestly only an idiot when it comes to electrical circuits which is unfortunately a third my course, if you want to drop explanations of concepts relating to circuits I will read, but right now focusing on getting at least 70% on exam in 4 days.

>>8976968
here, take it from the gorillaposter who's roleplaying as a mathematician:
>>8976151

hopefully you will be convinced that the same holds to all integer n and not just n=1

Sorry, hopefully this works

Problem: Use the relation [math] \frac{1}{a^2-x^2}=\frac{1}{2a}(\frac{1}{a+x}+\frac{1}{a-x}) [/math] to find the nth derivative of [math] \frac{1}{a^2-x^2} [/math]

Solution: [math] \frac{n!}{2a}(\frac{1}{(a-x)^{n+1}}+\frac{(-1)^n}{(a+x)^{n+1}}) [/math]

How is this found?

>>8976647
>>8976654
i like how they deleted your images i hope you got banned too you shitty troll

>>8976974
>divisibility
>real numbers
If the gorillaposter wrote that then he's just as much of a moron as you are.

>>8976983
>he's just as much of a moron as you are
i'll accept this

>>8976979
You need to know 3 things: the sum and product rules for derivatives, and the derivatives of [math] \frac{1}{a \pm x}. The rest is just plug and chug.

>>8976996
should be [math] \frac{1}{a \pm x} [/math]

>>8976969
bumping

come on this should be easy to answer

>>8977004
>>8976969
never mind, it's not i it's L

>>8976979

Without using the relation you have to use chain rule

[math]\frac{d}{dx} \frac{1}{a^2 + x^2} = -\frac{1}{(a^2 + x^2)^2}\frac{d}{dx} x^2[/math]

and so on. Using the relation eliminates the chain rule (except I guess the second term)

[math] \frac{d}{dx} \frac{1}{2a}(\frac{1}{a+x} + \frac{1}{a-x}) = \frac{1}{2a}(\frac{d}{dx}\frac{1}{a+x} + \frac{d}{dx} \frac{1}{a-x}) [/math]

>>8976643
Should I Subscribe to NYT?

Best resources to study for GRE? Hoping to get 168+ Q, 163+ V, and 5+ W

I have a discrete math midterm due tomorrow, where can I find someone to check my work before then?

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Hope some CS fags can help me out. I got this question on an exam recently (pic related)

The way I understand it, to contradict the pumping lemma, given any m, I need to find some word w such that for any decomposition w =uvxyz satisfying |vxy| <= m and |vy|>= 1, the v and y part can be pumped in such a way that the resulting word is not in the language. However, I couldn't figure out how to do it and it seems impossible to me, here's my reasoning:

Suppose there exists such a word w that i can use to contradict the pumping lemma. Then w cannot contain the string ab or ba, since otherwise uvxyz could be such that vy = ab or vy = ba, which can be pumped without violating the equation that defines the language (adding a's and b's in equal amounts). Similarly, it cannot contain aac, aca or caa anywhere, since a uvxyz with vy equal to those could be pumped without producing any word outside the language (adding two a's for each c).
So w cannot contain the letter a, because it cannot be neighboured by the letter b, and if it is neighboured by c there is at least one c for each a, and such a word cannot be in the language.

I'm probably misunderstanding something, so any help is appreciated.

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In this problem set, I am stuck on c. Wouldn't the big-O limit be infinity, since the tree can go on forever?

Also, in this problem set: http://www.chegg.com/homework-help/questions-and-answers/work-fsas-alphabet-b---give-regular-expression-draw-fsa-language-strings-two-s-b-give-regu-q22460413

The last problem below c.. how do I define that with a regular expression?

good answers will get some bitcoin if you post address

>>8977623
what class is this? some kind of discrete math / combinatorics?

>>8977810
or would this simply be 4, since the tree is only 4 nodes deep, thus the maximum word length is 4.. surely it can't be that simple?

>>8977813
It's about formal languages, automata, computability and complexity

>>8977819
oh cool. Wish I could help but I'm only in introductory discrete math

>>8977810
isn't it just O( log|S| ) , because the number of states is at most 2^(max word length)

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What steps (aside from an heroing) can I take to develop a respectable work ethic? I'll probably be a brainlet forever now, but I think if I can at least work hard I'll be able to live with myself.

Thanks.

>>8977935
>What steps (aside from an heroing) can I take to develop a respectable work ethic? I'll probably be a brainlet forever now, but I think if I can at least work hard I'll be able to live with myself.


do a little bit of studying every day without fail, just an hour or so over a period of time will get progress and be inspired to do more.

>>8977057
no

https://www.youtube.com/watch?v=pSu2arM9zJU

>>8976643
When finding inverse of 3 x 3 matrices
Why do keep I getting wrong answer for inverse when inverse exists If i'm successfully transforming left side into identity matrix

Integral of Im(z) dz from z = 1 to z = 1 − i along the curve C given by z(t) = 1 − it

am i stupid or is x(t) gonna be t = 1 while y(t) will be given curve 1 - it?

>>8976643
If I have a sealed container with a constant number of gas particles in it, and if I suddenly reduce it's volume by a factor of 0.5 will it's pressure double or will it's temperature double?

Astrophotography is science too
tldr do cassegrain need modding to achieve DSLR backfocus?

I own a dobsonian newtonian for visual viewing but I decided to attach my DSLR to it. Turns out it can't achieve backfocus properly so I had to mod the telecope's mirror a few inches up in the tube assembly. It works now and I'm happy with that and all but I was looking at something like cassegrain for the DSLR. Do cassegrain telescopes require any modding to achieve DSLR backfocus or will it more or less work out the box?

I want to learn a bit of math. is the rudin book a good choice if I know highschool math? just want to prep a bit before choosing a univ next year

Is there any similarity between a vector space ans a fiele. Im studying linear algebra and id like to know when ill learn fields. Im not sure if its covered in this subject.

Ive been looking at EE professors at my uni and found one doing cool photonics related research and he is looking for undergrads. I have not taken any photonics classes and will not until maybe spring '18. Will he reject me for this, or is there a chance i can still get in?

>>8976979
>How is this found?
By induction.

Can you get magnets that only stick to certain materials and nothing else?

Okay /sci/, I might have a really dumb question but it's bothering me. If you type 10^2^3 in the Android calculator you get 100,000,000. But if you do it step by step (10^2=100 and then do 100^3) you get 1,000,000. The only way I can get it to work is when I do 2^3 first and then do 10^8, but aren't you supposed to do it from left to right? I feel like a retard right now

>>8979249
theres a chance but he will probably recommend you take his classes asap

>>8979612
10^2^3 is different from (10^2)^3
for clarity's sake you should probaly still write 10^(2^3) though

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So what is it /sci/?

>>8979689
>anime girl
you failed the autism test

>>8978975
The scalar of a Vector Space are (by definition) a field.

>>8979615
ok..I probably will as soon as i can, need to take EM field theory this fall then spring i can but no sooner way really well thanks anyways

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>>8979692

>>8979689
[math]6\sum_{n=1}^{\infty} n[/math]

>>8977836
I don't know, is it?

>>8976961
> prove 2 + 2 = 4

Lets use peano axioms here.
0 = {}
1 = {{}}
2 = {{}, {{}}}

2+2 = 2 + 1 + 1 = {{}, {{}}, {{}, {{}}}} + 1 = {{}, {{}}, {{}, {{}}}, {{}, {{}}, {{}, {{}}}} } = 4

My question is posted here:

>>>/wsr/332728

Please, if you know any discrete math, help an anon out :-) I can even send some bitcoin if you'd like.

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How many ways can you pick (n-2) objects from a set of n objects with repetition?

if i start injecting myself with estrogen at aged 80, will i live longer?
>>8979856
does order matter? if so it's [math]n^{n-2}[/math], otherwise it's [math]\binom{2n-3}{n-2}[/math]

>>8979908
how did you come to that conclusion?

>>8979918
what conclusion? the combinatorics or estrogen stuff?

There was this extensive pocket book for engineers that everybody jerked off to saying it was fucking amazing.

I hear about it a bunch but now that I'm looking for it I can't find it, does anyone know what I'm talking about?

>>8979922
lol the combinatorics conclusion, I don't have any evidence backed input for the estrogen stuff, but it seems counter intuitive at least

how many distinct labelings are there for the two nonisomorphic labeled tree of 4 four vertices?

How would you find this for the 3 labeled nonisomorphic trees of 5 vertices?

If it's asking me to prove x^3-1/x-1=1+x+x^2 would just doing
>(x-1)(x^2+x+1)/(x-1)
>=x^2+x+1
be valid?

>>8979695
Wait what? The scalar? You mean the norms?

>>8979973
the way you wrote it is a bit unclear but yeah multiply both sides by (x-1)

why the fuck do plots in mathematica default to a non-square aspect ratio

>le aesthetically pleasing golden ratio maymay
fuck off

this has to be the most misguided use of the golden ratio i've ever seen

actual retard here

I've been trying to play around with quadratic functions, and was trying to derive a quadratic-equation equivalent for the standard form (f(x) = a(x-h)^2 + k) by solving for x at 0:
a(x-h)^2 + k = 0
a(x-h)^2 = -k
(x-h)^2 = -k/a
x - h = +-sqrt(-k/a)
x = +-sqrt(-k/a) + h

When I plug the appropriate numbers in, I do get the right answers, but the signs are flipped compared to the equivalent function (f(x) = ax^2 + bx + c) with the quadratic equation.

What does mathematics mean by this? I must be deriving it wrong, but I can't quite point out where I'm fucking up

can someone explain how the operation on (x1,x2) and (y1,y2) leading to (x1y1,x1y2+x2) is an affine transformation? how can i interpret this as point preserving? i feel so stupid jesus.

So just how broad is the definition for a "function"? Can I have one in three+ dimensional space? Can it be a surface, so long as each point on the XY plane has only one Z? Would a trail through space be considered a function, such that each X gives you only one Y,Z pair?

>>8979689
You can't devide by zero you fuckhead.

anybody has resources on nmr/xray scattering/ms that might be "easy" enough for an chem undergrad?

>>8979991
Check here
https://proofwiki.org/wiki/Definition:Vector_Space

>>8980207
Yes, the definition of a function is probably the broadest thing in math after a set.
Also, yes to all of your questions.

>>8978715
Typically cassegrains do not because they almost all come with 90 deg prisms which means the eyepiece is actually quite far from the back of the telescope. I've used 4 different makes and they required no modification. Saying that I'm sure there will be some cheap ones out there that do not. If in doubt google the exact telescope you're interested in see if anyone has used it for astrophotography. Most of the mid ranged telescopes (apart from dobs) are designed to be able to do astrophotography without modification. Personally I have a nice corrected Newtonian where the eyepiece sits very far out just so it can be used for imaging.

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Hello friends, brainlet here.

Is pic related still valid? or is there a new version of this?
I want to become a NukE, but I really want a solid foundation to keep learning math/physics on my own while I study.

>>8979941
suppose order matters. then if you have a set of size n, for the first choice you have n possibilities; the second n*n; the third n*n*n; until you have [math]n^{n-2}[/math] possibilities for n-2 choices.
tbqh i dont get the second intuitively, but you use the formula [math]\binom{n+r-1}{r}[/math] where r is the number of times youre selecting from the set

>>8980190
can you post an example with the actual numbers i dont really understand.
your derivation is correct though.
[eqn]ax+bx+c=0,\qquad \text{with }b=-2ah \text{ and } c=-ah^2+k\\
ax^2-2ahx-ah^2+k=0\\
a(x-h)^2+k=0\\
a(x-h)^2=-k\\
(x-h)^2=-k/a\qquad (a\neq 0)\\
x-h=\pm\sqrt{-k/a}\qquad (k/a\leq 0)\\
x=h\pm\sqrt{-k/a}
[/eqn]

why don't they put a flamethrower or someshit in the oven so you can preheat it faster if you're in a hurry

i probably could have patented that idea and made millions

>>8980545
>i dont get the second intuitively
You have n of the same things, and you wanna put them in k slots.
You can think of the n things as dots and the slots as k-1 bars. Like this:

*|****|**|****

So, you have n+(k-1) stuff and you want to find all the ways where you put the k-1 bars.
All those ways are C(n+k-1,k-1).
Equivalently you can think of where you wanna but the n dots: C(n+k-1,n).

In the guy's problem:
- the slots are there to count how many times he picked an object of from the {a1,...an}, therefore you have n slots, which means n-1 bars.
- and the dots are there to fill the space between the bars and they are n-2 in total.

Thus it is C[ (n-2)+(n-1) , (n-1) ] = C[ 2n-3 , n-1 ] = (2n-3)! / ( (n-1)! (n-2)! ) = C[ 2n-3 , n-2 ]

What is the relation between eigenvalues and singularity of a matrix?

>>8980566
After trying another example, I must have done the first example wrong. Silly me.

Thanks for boosting my confidence, anon!

>>8980605
Watch this
https://www.youtube.com/watch?v=PFDu9oVAE-g

Working through Griffith's Electrodynamics right now, and I want to make sure I got this right since I've seen lots of different answers online.

Problem 1.4 asks us to find the angle between the body diagonals of a cube. What I did was define a unit cube and the body diagonals ((0,0,0), (1,1,1)) and ((1,0,0), (0,1,1)), turned them into vectors A = <1,1,1> and B = <-1,1,1>. Then I found the dot product component wise with A.B = 1*-1 + 1*1 + 1*1 = 1, and set that equal to |A||B|cos(theta) = 3cos(theta), then solved, finding theta = 1.23. Is this right? I've also seen theta = pi online, which kinda makes sense (especially since it's kind of a Schelling point whereas 1.23 seems arbitrary) but I dunno.

(Sorry for no TeX, I'm on my phone)

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>>8976643
Why is (x+y)/2 (assuming x>y) the same as y+(x-y)/2

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>>8980941
example:

x=9, y=5

(x+y)/2=(9+5)/2=7
7 is the average of 5 and 9, halfway between them on the number line

(x-y)/2=(9-5)/2=2
2 is half the distance between 5 and 9
5+2=7

>>8980959
You're great at explaining things, thanks so much anon

I am brainlet and doomed to be wagecuck.
Should I kill yourself instantly, or die trying to get more knowledge while I can?

I know what an eigenvalue is.
Now this paper I'm reading mentions a "principal eigenvalue"
What's that? English also isn't my native language btw

>>8981030
It is the eigenvalue with the greatest magnitude. i.e. max{ |λ1|, ... , |λk| }.
Intuitively the subspace of the principal eigenvectors it is the direction where the operator "does" the most.

>>8981125
Thanks friend

how to climb out of calclet hole and learn calc1, 2, linear algebra? what books/sites do you guys recommend?

>AP Calc AB
failed, we were supposed to do it online while the teacher taught another class and never actually helped

>Calc I
fail, didn't review foundations and only did well on one test

>Calc I again
too focused on trying to kill myself to math, fail

its not even for school, i just want to learn it. everything from optimization onward was really interesting to me, even though i wasn't good at it.

>>8981321
nevermind i forgot to look at the fucking sticky.

Why don't power plants use giant diesel engines and LNG instead of a gas turbine?

What happens to matter that falls into black holes? Is it destroyed?

>>8981330
reciprocating diesel engines require more maintenance. turbines really only have one moving part and once they are up to speed the internal forces of the machine do not change much. that is not true for recip diesels.

is there any merit in publishing to arXiv from an employers perspective? like is it worth mentioning?

>>8981429
ehh, depends on the position. R&D or academia, i'd say yes. your standard cube drone position? nah.

How did DNA start to replicate? What initiated it? We have no idea I'm sure, but what are the theories? I've always been perplexed by the rules of biological systems. They seem so afraid to explain it in chemical and physical terms in school.

If we built a massive steam engine around Earth, could we reverse terrestrial entropy?

>>8981350
No. I mean, Stephen Hawking said some bullshit about matter being destroyed in black holes but continuing to exist in alternate universes, but that's retarded so the answer is no.

>>8981504
https://en.wikipedia.org/wiki/RNA_world

The theory is that RNA evolved first, maybe even before cell membranes or metabolism.

Nobody has created a self replicating organism from scratch in a lab, and we aren't precisely sure how life started or what the first life looked like, but it's not that hard to make cell membrane, amino acids, or other very basic building blocks in simulated early-earth conditions.

https://en.wikipedia.org/wiki/Abiogenesis

>>8981350
Best guess, it turns into Hawking radiation and is slowly radiated back out as the black hole shrinks.

I'm not sure if this is /biz/ or /sci/.

How do you auction off a lot of items at the maximum price if no one buyer has enough money to pay for the entire lot?

The example I was thinking of was carbon taxes. You could a quota, sell the carbon emission thingies to the highest bidder, and then let the market decide how valuable carbon emissions are worth and who should get to emit.

The issue being, no one company could afford to buy all of it, and you want the government to

A: Score as much money as possible out of the deal

B: Distribute the rights as efficiently as possible.

I'm switching to Computer Science.
Did I fall for the meme?

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What's a blockchain?

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Are these the true patrician pencils? My surveying of other AP students leads me to believe so.

>>8981691
>fake wood
>screw to get more lead instead of pressing a button
>can't twist to get more eraser

EWWWW

>>8976643
Test.

>>8981697
Congrats dood you did it

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>>8981691
>pic
lol what the hell

bic makes good mechanical pencils. look for the ones with thicker/fancier designs with an ergonomic rubber grip

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>>8981691
Not paying a little extra to get a Kura Toga, and extra leads...?

Is Mensa a meme?

>>8982006
yes

try this: http://test.mensa.no/

chances are that you'll get a pretty high score, it's too easy

they just want your membership $$$

even if iq tests were legit there wouldn't be much of a point to go to those meetings, it's just a circlejerk

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Is it possible to figure out someone's lens prescription if you only had their glasses lens or contact lens? Do you just shine light through it in certain ways and measure the curvature?

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what are the long term effects of affirmative action in STEM?

Less science and more engineering, but is there a way to convert Shore D hardness results to Rockwell M? Specifically for PC if it helps.

>>8982120
https://onlineconversion.vbulletin.net/forum/main-forums/convert-and-calculate/14581-rockwel-m-r-values-to-be-converted-to-shore-d-values
>Shore is usually used for softer material such as plastics while Rockwell is used for hard material such as steel.

>>8982138
I know what they are (and found that page already), but my issue is that I need to give a RockwellM result of a material, and I only have acess to a ShoreD tester, and the material is more suitable for ShoreD. I wondered if I could convert the results.

>>8980207
A function F is a set of ordered pairs <x,y> with the constraint
(<x,y1> in F) and (<x,y2> in F) => y1=y2
IOW, there must be at most one y for any given x.

The sets from which x and y are drawn (domain and codomain respectively) can be anything.

> Can I have one in three+ dimensional space?
Yes.
> Can it be a surface, so long as each point on the XY plane has only one Z?
Yes. Domain is R^2, codomain is R.

> Would a trail through space be considered a function, such that each X gives you only one Y,Z pair?
Yes. Domain is R, codomain is R^2.

Also you can have parametric curves (R->R^3) and surfaces (R^2->R^3), which avoid the single-value issue by introducing additional parameters and making all of the coordinates functions of them.

anyone here actually buy the usnews ranking shit? Looking for top 50 EE grad schools ranking from there

Theorically, the proton of a CH group bonded to an OR group (and two other sp3 carbons) should have an 1H-NMR chemical shift of around 3.7. Is a shift of 4.0-4.6 justified by being part of a (saturated) cycle?

>>8982341
uninstall

>>8982380
a lot of reasons. first is community college transfer students. going to CC for the first 2 years cuts your overall student debt in half. there is scholarships, but more importantly are paid internships and part time jobs.

you are paying a premium for "muh college experience" of going to a University for the entire 4 years and sitting on ass outside of class time.

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help.

I'm getting tested on this tomorrow. Look at battery/cell symbol and tell me which direction current flows in in (c) and (d) please. did they arbitrarily switch which way the anode and cathode are in their symbol? in (d) only makes sense anti-clockwise (see "forward bias"), in (c) it only makes sense anti-clockwise.

mistake or am I missing something? This is important because evey time I've revised the textbook I've just ignored this whole aspect of electrical circuits. No friends or teacher to ask.

>>8982437
hitler should have gone after sideways picture posters instead of jews

>>8982437
>>8982439
sorry senpai. any clearer? I really need an answer on this.

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>>8982443
>>8982437
>in (c) it only makes sense anti-clockwise.
in (c) it only makes sense clockwise*
also new forgot pic

the fuck is the integral of e^x^2 dx
i googled it and get something called erf which idk what it means

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HOW THE FUCK THEY FIGURE THIS FFS?

>>8982512
https://en.wikipedia.org/wiki/Geometric_series

>>8982514
Alright what about the second?

>>8982544
it's trivial, look at what's on each side

>>8982545
Clearly it's not fucking trivial cause I thought about it and couldn't figure it the fuck out.

>>8982555
it is trivial, look again

>>8982557
So you don't fucking know it yourself. Predictable.

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>>8982561
at least take another look brainlet before spouting off nonsense, it's not hard

also no need to swear

>>8982564
Hahaha I get it at last. What a riddle!

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>>8982570
good work brainlet :)

>>8982490
"erf" is the error function; it's defined as the integral of e^(-x^2).

*Most* functions don't have an antiderivative which can be expressed in terms of standard functions. Of those that do, many of them can only be expressed using "standard" functions whose definition is actually "integral of <whatever>".

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Let's take 2 fucking series SA and SB. After nth term every a is smaller or equal to b.

By the comparison theorem convergence of SB implies convergence of SA (and obviously this implies an implication for divergence).

But SURELY SA could be convergent and SB could be divergent?!

WHY THE FUCK NOT?!

Zorich says that in such a scenario they "converge or diverge together". WTF?!

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>>8982612
>But SURELY SA could be convergent and SB could be divergent?!
yeah, so what?

>>8982617
ON THE FUCKING PIC IT SAYS "THEY CONVERGE AND DIVERGE TOGETHER" FFS. CLEARLY NOT FUCKING TOGETHER!

>>8982612
>By the comparison theorem convergence of SB implies convergence of SA (and obviously this implies an implication for divergence).
Yes, SA divergent implies SB divergent.
Neither of these are "if and only is" statements though.
>But SURELY SA could be convergent and SB could be divergent
Yes this is possible. These two series fit neither of the implications

>>8982625
SO WHY THE FUCK DOES IT SAY ON THE FUCKING PIC "THEY CONVERGE OR DIVERGE TOGETHER" WHEN IT'S SUCH OBVIOUS FUCKING BULLSHIT. RETARDED ZORICH?!

>>8982628
It's true for that example. It's not true in general

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>>8982628
you're clearly the retard here

learn to read, maybe much much more slowly than you currently are, zorich is right and you're just a brainlet

>>8982630
SO WHY _____________________THE FUCK__________________ IS IT TRUE FOR THAT FUCKING EXAMPLE?

I DON'T SEE IT.

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>>8982634
by the comparison test brainlet
can't you read?

>>8982639
WHAT COMPARISON TEST FFS?! WE JUST FUCKING ESTABLISHED THAT IT DOESN'T IMPLY THAT THEY "CONVERGE OR DIVERGE TOGETHER" FFS!!!

>>8982634
[math]\frac{1}{n(n+1)}> 0 [/math] [math]\forall n>2[/math]

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>>8982645
but it does, look at the inequality he wrote

did you even read the picture you posted?

>>8982555
1/(n+n) is the smallest fraction in that sum. The sum has n terms. Do you see it now?

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>>8982647
>>8982648

I DON'T FUCKING GET IT.

Look. Let's say the series on a middle term of the inequality is divergent. That means so is the last one. But the first one CAN STILL BE FUCKING CONVERGENT WITH NO CONSEQUENCE.

SO WHY THE FUCK DO THEY "CONVERGE OR DIVERGE TOGETHER FFS?!

>>8982681
>But the first one CAN STILL BE FUCKING CONVERGENT WITH NO CONSEQUENCE.
no it can't, if the last one is divergent so is the first one brainlet

therefore they converge or diverge together

>>8982684
> if the last one is divergent so is the first one brainlet
WHY?!

>>8982699
look at the series brainlet

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FINALLY FUCKING GOT IT. USELESS KEKS ITT

Is water quality management a respectable career? I like water resources science.

>>8982612
Because [math]\frac{1}{(n-1)n}-\frac{1}{n(n+1)}=\frac{n+1}{(n-1)n(n+1)}-\frac{n-1}{(n-1)n(n+1)}=\frac{2}{(n-1)n(n+1)}=\frac{2}{n^3-n}[/math]. The difference converges (bounded by geometric series) so the convergence of either [math]\sum\frac{1}{(n-1)n}[/math] or [math]\sum\frac{1}{n(n+1)}[/math] is implied by the other, since the pointwise sum of two convergent series is convergent. Importantly we also then that the difference [math]\sum\frac{1}{(n-1)n}[/math], [math]\sum\frac{1}{n^2}[/math] or [math]\sum\frac{1}{n(n+1)}[/math] since the difference between [math]\sum\frac{1}{n(n+1)}[/math] and [math]\sum\frac{1}{n^2}[/math] must also converge.

why do kids scream alot? i remember back when i was a kid i didn't scream like a motherfucker.

nowdays every kid who is under 10 is screaming like an animal

>>8982721
You're a retard.

>>8982759
Confirmation bias

>>8982755
> The difference converges (bounded by geometric series
What series?

> pointwise sum of two convergent series is convergent
First time I'm hearing this. What the fuck is pointwise sum?

>>8982787
>What series?
Nevermind that, it's a mistake.

>First time I'm hearing this. What the fuck is pointwise sum?
If [math]\sum_0^{\infty} a_n[/math] and [math]\sum_0^{\infty} b_n[/math] converge, then so does [math]\sum_0^{\infty} (a_n+b_n)[/math].

>>8978681
pressure is force by area, not volume. and the temp change depends on the type of gas.

>>8979908
>if i start injecting myself with estrogen at aged 80, will i live longer?
no. you have to live like a pussy all your life, to maximise statistical effects.

Why the fuck are all EEng lecturers on Youtube Indians?

There used to be a Python package called Numeric, which is deprecated now and replaced by Numpy.
For a university research project, I need to use some old software that was still written with Numeric.
I am also on Linux.
Any chance of getting a package for Numeric somewhere?
The package manager (aptitude) doesn't have it

Is this thread just for math questions?

If not,

Is there any instances in nature which are completely random?

Animals, plants, bacteria, waves, anything

>>8983143
define random

Is mining engineering a meme discipline?
My country has a pretty big mining industry, but I don't know about how is it on other countries and I want to get out of this shithole as soon as possible.

>>8983157
Lightning is 'random' but realistically it's choosing the path of least resistance.

A process/decision that has no underlying input into it determining the outcome.

I'm wondering because apparently DNA during cross over is random which seems odd because I can't think of many things in nature that are truly random.

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What should i study to understand probability theory? I understand a decent amount of set theory symbology and i took calc 2. What more do i need?

I wanna start a math blog.

What sites are more appealing to this shit? tumblr? wordpress?

>>8983128
http://www.numpy.org/old_array_packages.html

But I would recommend just converting the code into numpy if you can:
https://github.com/qsnake/numpy/blob/master/numpy/oldnumeric/alter_code1.py
https://scipy.github.io/old-wiki/pages/Converting_from_Numeric.html

>>8983176
You'll need to understand measure theory, if you really want to get into it.

>>8983254
Thanks man

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How can white light contain all the colors if the colors are different wavelengths? How can a wave have multiple frequencies?

>>8983252
>What sites are more appealing to this shit? tumblr? wordpress?
just post on /sci/

>>8983382

NO FUCK THAT

I want my own meme blog

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I am in need of some new reading. Just finished Calculus series and Discrete Math intro series (ending with big-O notation and finite state automata). I'm interested in something that's 'off the beaten path', as in not something a pure/applied math major would be required to take.

>>8976643

I've spent way too much time on this problem:

What is the simplest way you could explain how to calculate if a given ray represented as a normalized 3d vector intersects with a sphere given as a 3d point with a radius?

I need like extreme retard brainlet 50 iq explanations. Even partial explanations or tips are welcome as long as they are simple.

>>8982564
>gorillaposter has another episode
>gets his images deleted
>comes back after 3 days
did you really get banned lol

>>8978126
you're doing it wrong

alternatively, the determinant is zero

>>8980525
just do Spivak, if you can't then get a proof book, any one.

>>8983566
Nice to see a fellow UW anon here

>>8976643
I want to work for NASA as an astronautical aerospace systems engineer, or the closest thing possible and open, and help work on spacecraft

Does anyone on /sci/ actually do things for humanity in general or just shitpost about what they know

>>8983682
I'm only larping as one, really I'm a CC student who hops to go to grad school there

>>8983355
The same way a sound wave can. A chord, for example, is a mix of multiple frequencies. Light (and sound) waves of different frequencies can add without interfering, so you can have a mixture of frequencies that can be individually resolved.

Also, white light from a thermal source, such as the sun or an incandescent light bulb has a mix of all (visible) frequencies, but other "white" sources, such as a computer screen, do not. A "white" part of a computer screen is a mix of light of three colors (red, green, blue), and therefore three frequencies. The three colors and their intensities are chosen so as to fool the eye into thinking the light is white.

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>>8983355
waves can be added together

https://www.youtube.com/watch?v=r18Gi8lSkfM

>>8983566
Bump

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>>8983639
>did you really get banned lol
I've been getting banned regularly for almost 8 years now, 3 day bans fly by.

>>8980525
>Is pic related still valid?
No, that looks like a memelist.

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Hello /sci/
Let's pretend I am a complete brain dead retard who has done little to non math in his life.
How far can Khan Academy take me and where should I go to advance further than that?

WTF IS 1/N INFINITE SERIES DIVERGENT FFS?! THE LIMIT IS FUCKING 0!

WTF?!???!?!?!??!??!!??!

>>8984037

It can take you well from kindergarten to undergraduate calculus. I'd recommend that you follow Khan Academy along with a textbook.

WTF IN CAUSHY TEST IF ALPHA = 1 IT'S EITHER ABSOLUTELY CONVERGENT OR DIVERGENT? WHY CAN'T IT BE JUST CONVERGENT?!

>>8984052
Any recommendations?

>>8984058

There is a comprehensive math guide on the sci wiki.

http://4chan-science.wikia.com/wiki/Math_Textbook_Recommendations

>>8983721
Ahhh thanks. I didn't really understand that video, but now I see how waves can be added together, by becoming a wave that isn't a sine wave.

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Can someone help me write out the domain of this function? I know that y has to be positive and that x^2+y^2 has to be greater than 1 but I have no idea how to write it out mathematically.

>>8984197
[math] \{ (x,y)\in \mathbb{R}^2 \mid x^2+y^2>1, y> 0\} [/math]

>>8984206

Thanks friend.

>>8984043
>>8984053
shut up and study, faggot

What's the difference between x ∈ Σ and x ∈ Σ*, where Σ is some alphabet and x is an element of some string?
I'm not sure how the Kleene closure makes them different.

>>8983566
Bump

>>8981565
Pls respond

>>8984386
Linear Algebra for sure. And learn it really well.

>>8984409
Well I am required to take that class anyway, so I kinda wanted to avoid redundancy. I know there's benefits to studying it additionally, but that's not what I'm looking for.

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>>8976643
Simple one.

Good books on nuclear engineering? I checked the sticky but nothing. All other books recommended by /sci/ have been very good, I trust you guys over google or amazon reviews

>>8984418
Oh I misread.
Well, if "discrete" math and basic calculus is all you have done, you can't really read anything off the beaten path.

Is Ross's "Statistical processes" sufficient groundwork for Bayesian inference aka Gelman?

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Took pre-calc at age 15 in sophmore year, now 18, haven't done any math since (because I didn't have to and at the time I was falling for other memes)

Would this be a good starting point? I want to go from this and continue through III, then learn proofs, then diffeq, then algebra, then topology, then analysis. r8 my plan

>>8984501
I would learn proofs now but that's just me. They don't require any math past high school algebra (unless you're dealing with a domain specific proof, like a trig proof).

But as for the calc book yes, I think any book you like and have access to is fine (though many will argue about this). Progress is the most important thing though. I went through James Stewart Calculus Concepts and Contexts and hated it, would've likely enjoyed Spivak much more. Just know there's options out there, sometimes these textbooks only teach you computational methods, and little to no proofs and deeper concepts.

>>8984501
>>8984508
And as for the order of learnin's, I would personally take it one step at a time. Start thinking about what sounds cool after you finish the calc book. Another option would be to study linear algebra and Calculus concurrently.

>>8984424
OK, I thought this might be the case. Is there anything you might recommend then? Going heavy into geometry sounds cool, but I don't know if I have the tools. Perhaps I will study linear algebra after all, so that by the time class rolls around I will be able to allocate more study time to other subjects..

>>8984513
>Another option would be to study linear algebra and Calculus concurrently.
I've considered this. Do you know anything about this textbook? >>8984501

>>8984354
Just Google it faggot:
A string from the Kleene closure can not contain every character from an infinte alphabet. Σ∗ is, by definition, the smallest set containing Σ, the empty word, and stable by concatenation. With that, you cannot reach infinite strings. In other words, Σ∗ is the set of all finite strings on Σ.

Hello nerds. /R9k/ here can u help me with math?

7% of percent of greek population support golden down (Greece population is 10millions) what probability that if I call for 1000 random Greeks they would support golden down?

>>8984043
Learn what implication means, [math]A\rightarrow B[/math] (A implies B) does not necessarily mean [math]B\rightarrow A[/math]. I had a class in formal logic before I started calculus and it helped a lot.
[eqn]\sum a_n[/eqn] diverges if [eqn]\lim_{n\to\infty}a_n \neq 0[/eqn] However, if it does go to zero we know nothing and must try something else.

>>8984520
No, nothing. Other than that I almost bought it at on a whim at goodwill awhile back. I'd imagine it's just fine though :) If you get into it and things get a bit stale, you can always switch to a different book too. I'm assuming you must have a physical copy of this book?

>>8984516
>Is there anything you might recommend then?
I always wished I studied measure theory, even though I didn't pick that class in my uni (I am gonna study it by myself eventually) because you can understand things like probability and statistics as well as many other subjects much more deeply.

>>8984628
Oh ok, I was actually just reading up on that last night - I had never heard of it until then. To really understand measure theory, what prerequisites are required?

How concerned should I be about AI overtaking humans?

>>8984717
Not concerned unless your line of work could be easily automated

>>8984721
this

and lol @ people thinking non-pajeet programming will be automated. at best machine learning will be used for tools used by programmers like better compilers. if AI were to advance to the point where programming could be fully automated you would have bigger things to be concerned about.

>>8984601
nah I ripped it from libgen I'm just gonna read it and do the problems I figure theres not much more to it than that

>>8984717

What I think you should be asking is whether you should fear for your life not just your livelyhood.

>>8984738
Oh ok, why did you pick a book you're so uncertain about?

>>8984731
People on here also seem to think that AI will replace mathematicians. If the singularity ever occurs, mathematicians would be one of the last to become unemployed.

>>8984669
You are going to need real analysis. The more analysis, the better (e.g. metric spaces, complex analysis, general topology etc), but knowing real analysis is enough.

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Can someone give me some career advice? I'm just about done with my lower level requirements for a math major, so I have to start making some hard and fast decisions between which upper level classes to take, primarily between the three categories of pure, applied and statistics. I look at it as follows:

>Pure
The most interesting and purdy math, but almost demands a PhD for real usefulness and a return on investment.

>Applied
Probably rather employable, and perhaps useful as a BS as well.

>Statistics
I'm very much into probability and statistics and am learning towards this, despite being interested in what is taught in the pure (and applied, to a lesser extent) math curriculum. I feel it is the most employable as a BS, and may have the easiest entry into PhD due to the sheer industry demand for it.


The caveat here is that I have an absolutely horrible transcript (fortunately not in my math classes, but have accumulated a total of 6 F's), However, on the upside, I've been pulling straights A's more recently and if I continue to do so will graduate with a 3.8+, thanks to classes retake not counting. All of the F's have been at community college, with my Uni transcript so far being impeccable. Pls no bully.

Is there any hope for a PhD? If so, what would you recommend? It took me some time to realize all I wanna do is research.

>>8984924
>>8984924
Also, I'm interested in cryptography (and therefore) number theory, how might that play into a statistic and probability focus?

>>8984826
I'm not uncertain about it I heard about it in the wiki, I was just seeing if anyone here had read it

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Who's the dude between Galilei and Newton?

>>8984526
Do you pick the 1000 random greeks one by one or you take them everybody at the same moment?

>>8984526
the probability that all 1000 of them would support golden dawn?

>>8984526
Assuming your group of 1,000 Greeks was randomly chosen from the population, the odds would be 7/100 that any given member of the group would support golden dawn.

On average, 70 out of 1,000 would support the group.

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>>8985069
nice

>>8985069
Why is Telsa even on there?

He's not a scientists by any measure.

>>8985069
Corey Feldman

>>8985100
is this bait?

>>8985082
One by one

>>8985087
That I understand but what probability that 100% of random chosen Greeks would support golden down? 1 to million or what?

>>8985137
You got an elementary statistics textbook?

That's a statistics problem, and I don't remember any of that class.

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>>8976643
Anyone know what kind of gauge/measurement device this is called? i saw it on a tour of a boiler power plant.

>>8984526
(0,07)^1000 = 1,25 x 10^(-1155)

It's zero

When applying for grad school, should you apply to PhD programs first and see if you get accepted, then resort to applying for a masters? Or do both at the same time? Of course, PhD is massively preferable since you get paid the entire time.

>>8985114
Tesla never published anything new or contributed anything to our understanding of science. At most, he was a tinkerer that did some work on AC motors, but even those had already been invented before him and the principles behind them were already understood.

>>8985234
Thermometer

>>8985248
When you apply for PhD if you get rejected they might just accept you for masters instead, all from just PhD application. All the schools I plan to apply for don't require a separate application, but check your target schools' websites. You could also apply for PhD and drop out with a masters if you feel it is not all you wanted while you are in it. Professors hate this so maybe just use as a last resort if you truly hate the phd route.

>>8985234
literally just looks like a thermometer that tracks temperature over time

>>8985234
We had one of these that tracked temperature and pressure in our calibration room.

If they showed crazy temperatures, we weren't allowed to calibrate (according to ISO) until the HVAC kicked in.

>>8985275
>>8985283
ah thank you i see that but i meant more like why is it in a circle and why are all the lines curved and is there a specific name for the type of thermometer of this sort

I know comp sci is a meme, but is it really? I'm getting a master's in math should I take any comp sci courses?

How do I stop being a lazy piece of shit?

>>8985347
Local a local area that is easy to walk in.

Begin at about a mile a day, and then escalate to 3-5 as time permits.

>>8985347
you don't. We will be this way forever friend.

>>8976643
Can a moon and planet share the same atmosphere for any reasonable length of time?

>>8985375
I'm almost positive that's a no.

Mostly because moons don't tend to find stable orbits within the comparably tiny distance from a planet that has an atmosphere.

Also, the moon would suffer from aerodynamic drag, which would cause it to eventually fall to the planet.

Also moons don't have a large enough gravitational field to support a stable atmosphere.

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CPSC guy here. Been reading Neil Degrass Tyson's new book and he claims that 2 seconds after the big bang the universe was a few light-years in diameter. How can the universe grow so fast from an infinitely small point? Doesn't this violate the fact that matter go faster than the speed of light?

>>8985452
That only applies to matter travelling within the space-time continuum.

The space-time continuum itself can travel faster than light and generally does.

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>>8985452
>Been reading Neil Degrass Tyson's new book

File: stupid idea.png (29KB, 335x601px) Image search: [Google]

29KB, 335x601px

Could this be an effective sustainable power plant? Ignoring the technical problems in building and maintaining it.

A deep hydroelectric well. Water falls on turbines, to produce electricity, at intervals where the water reaches its peak velocity, all the way down.
At the bottom it's heated to steam by the Earth and rises back to the top by low-powered turbines. At the top it liquefies in a condenser and runs through the loop again.
The well could be several kilometers deep, or to a point where the crust is hot enough.

is phd life total buttkissing, buraucratic, money begging wage-slavery? As an undergrad, getting paid to study sounds sweet, but I absolutely do not want to be a professor and would drop out then and there if that was my only choice.

So, is there also the option of just being a /comfy/ NEET researcher, not giving talks at conferences, lecturing, writing texts, etc etc?

can /sci/ come up with a way to eradicate all mosquitos on the European continent without also destroying the human population?

I need this for personal reasons

>>8985766
get a masters degree and earn some shekesl

>>8976643
how do I find the slope of the sine function on x=1.5, I keep getting zero as result?

>>8985909
It is cos(1.5) which is about 0.0707372016677029100881898514342687090850910275633468

>>8985909
http://www.wolframalpha.com/input/?i=D%5BSin%5Bx%5D,+x%5D+%2F.+x+-%3E+3%2F2

if i had to prove that 1/x is irrational if x is irrational, can i do it by contradiction showing that if 1/x was rational, then ax/b would equal 1, contradicting x is irrational?

>>8985982
a rational number by definition is a number that can be expressed as a fraction of any two integers, e.g. p/q

an irrational number by definition is a number that is not a rational number

if and only if 1/x is rational, it would be able to be expressed as a fraction of two integers, e.g 1/x=q/p, but this would mean x=p/q, meaning x is rational if and only if 1/x is rational, therefore 1/x is irrational if x is irrational

inb4 the gorillaposter overcomplicates this

>>8985995
but is the contradiction proof less valid than the contrapositive proof? i struggle knowing when to use one method over another.

What are the first signs you see in a unit/course that you should avoid taking?
For me its..
>the word "abstract" anywhere in the unit guide
>Male lecturer teaching the first half and female lecturer teaching the second half
>unit administered by all female staff

Number 1 and 3 are the most dangerous imo.

>>8986000
>but is the contradiction proof less valid than the contrapositive proof?
>>8986000
>less valid
proof is either flawed or it isn't, nothing in between

I am a guy.
I am scared.
I offered people to get together for a spontaneous Summercourse.
Basically: from Zero to Dummy.
Catch up in mathematics and learn some mathematical maturity.

Basically, we will meet in a room and crank on Khanacademy for 2-4h straight everyday and helping each other get straight for the next semesters as we repeat and expand on it throughout the vacation times on professional books.

Any tips on using Khanacademy?
I mean, yeah, mastery everyday for 30min is a given.
But I mean more on how can we make make it possible to get a lot done in 4h?

>>8986043
i thought excluded middle was abolished in the mathematics community!

The size of an AVL tree with n nodes is bounded by height h such that the following holds: [math]M(h) \le n [/math], where [math] M(h) = -1 + \frac {5-2 \sqrt 5} {5}r_-^h +\frac{5+2\sqrt5}{5}r_+^h [/math] and [math]r_-=\frac{1-\sqrt 5}{2}, r_+=\frac{1+\sqrt{5}}{2}[/math]. Show that [math] h \le \ld(n)*1.44+const[/math]

>>8985718
Would it work?

r-2\left(1-3\left(2r+4\right)\right)=61

>>8986107
The steam, or at least some of it, would condense before it reached the top of the loop. But seriously, you realise perpetual motion is impossible, right?

>>8986127
what the fuck does this code fucking translate to? anyone

>>8986107
>>8986130
that's not perpetual motion alright? it uses the heat energy of the earth, but such devices already exist, for such a system to work you btw need to have a difference in temperature

Can somebody show me a good example of adjoint representation of an Algebra?

is the sheffer stroke equivalent to such that?

like n is in the set Z | n=1-2k | k is in Z?

or am i using it wrong?

>>8985936
>>8985937
how do I go about this not by just taking the cosine of 1.5 but by finding the ds/dt ratio, is it possible?

>>8986288
i dont think you should use two strokes, usually you just use one to separate what set the elements exist in on the left and the conditions for them being in the set you're defining on the right

it sounds like you're trying to write

[math] \{ n\in \mathbb{Z} \mid \exists k\in \Z, n=1-2k \} [/math]

>>8986307
\Z?

>>8986317
should have been [math] \mathbb{Z} [/math], i'm too used to my macros

>>8986321
cool thanks. just out of curiousity when proving a theorem, is a contradiction of a conclusion the same as stating "our assumption is false which means its contrary is true"? like is it safe to assume if the assumption is something like n is even, then if i show a contradiction, the conclusion is that it's odd because that's the "contrary"? i just don't know if that's rigorous or not.

>>8984537
But how do you know it's fucking divergent? They claim it in textbook but it's like WTF?!

Started reading Gravitation by MBT (or whatever the fuck). Know math only up to limits and working at it.

Is it worth reading overall? It is like 50000 years old. Not that I would understand QM stuff anyway, of course.

>>8986506
integral test is probably easiest

>>8986712
>integral test
what is this again? i remember learning about this in calc but i completely forgot wtf it was

There are a shit-ton of threads on /pol/ about the yellowstone volcano erupting?

Will it erupt and if it does, what will happen?

>>8987030
>/pol/
they're probably full of shit, there's a lot of roleplaying and delusional stuff going on on that board