1. your cunt 2. f(x)=2x^2+x 3. Solve x for all zeroes of the function

>>75618587
0 or -1/2

>>75618587
>7th grade problem
this is a 18+ board

>>75618587
0 OR -1/2

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Well done.

But can you solve for extrema of the function?

>state of german engineering
No wonder german cars are so unreliable.

>>75618845
-1/4
ezpz

>>75618845
Define extrema

>>75618845
-b/2a for the x value to find the y value which is a minimum value because the leading coefficiant of the function is positive. This is high school level shit man. Either you are underage or retarded.

>>75618971
it's a parabola that points upward. it will have a minimum value only.

>>75618966
this
>>75618971
point minimum or maximum of the function

>>75618971
take a 1st derivative and solve the same way
2nd derivative for concavity etc.

>>75618587
really dude?

>>75619306
>thinking germans are smart
Biggest meme ever produced.

Why can't we just have a nice thread with anons asking simple math questions without judging their entire country?

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>>75619430
yeah it is not like half of the greatest mathematicians of all time are german

>>75619495
*Jewish

>>75619479
I am up for this

>>75619430
some are some dont. are you triggered by their posts? it was probably ikibey

>>75619529
I haven't heard of many Jewish mathematicians. There were many in stats and economics though.

>>75618845
4x +1 = 0

x = -1/4

>>75619529
>>75619575
nvm, I googled Jewish mathematicians and there's a fuckton of them I didn't know they were Jews

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>>75619479
>without judging their entire country
>AMERICANS ARE RETARDED
well that's /int/ for you. everyone is larping as a cunt

I am struggling with this one. Can someone solve this?

>>75619703
>tfw studying math but I know jackshit about differential equations
I fucking hate this subject.

>>75619703
isn't that the canonical A matrix for space state control? derivative (x) = Ax+Bu, where x are the state variables and u is the input signal?
Disregarding u, all you need to do to check for stability is the eigenvalues of the matrix, and if they tell you the sign of the elements that a 2x2 determinant (lambda*I -A) is very easy to calculate, for 3 is annoying

>>75619479
Simple math questions like this usually mean the poster is in high school. 4chan is for 18 and older.

>>75619980
the eigenvalues need to be negative numbers, that is they're on the left side of the complex plane, which is another way to say that the state variables evolve as sums negative exponentials instead of sums of positive ones.

>>75619980
you are right, but it is the next chapter so it hasn't been covered yet. looking ahead gives me anxiety. i am not very good at this so if I get a C in this class I will be happy

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ım too dumb for math

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Is this a correct approach? It is not an actual proof I just needed to show this holds true even though it is kinda obvious.

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>tfw prof started with delta-epsilon proofs

>>75620463
delta-epsilon proofs are the easiest to understand and so they are introduced early to boost your confidence. even introductory books like stewart cover them but usually in a not a very rigorous way.

>>75620341
The solutions of this (2x^2-1)^2+(2xy)^2=1 are the unit circle and the y axis.
The solutions of 2x^2-1=-(2y^2-1) is the unit circle.

Both equations hold iff and only if (x,y) lie on the unit circle.

The matrix S is of that form if and only if (x,y) are on the unit circle: i.e. x^2+y^2=1. Outside of the unit circle it is not of that form.

>>75620341
i guess it is, i would probably do it the other way around, do [2] first if x^2+y^2=1, then you substitute it into a=--a and you would get some bullshit like 0=0, but it's correct either way

>>75620463
Just always have in mind the triangle inequality and you'll be fine.

>>75620341
why do Eng schools make you do proofs? i was garbage tier at that but exceled in all the actual engineering courses

>>75620945
those are meme proofs. nothing to do with real proofs. it is calculus after all. stewart is a standard eng tier calculus book and the delta-epsilon limit definition is the only kind of "proofs" covered there. other than that they just give you a proof for "completeness" without requiring you to understand it or prove anything on your own. the fun stuff starts at the real analysis level which is obviously not part of any eng major.

>>75621122
still, every calculus course i took single/multivariable calculus and diff equations/complex analysis, was literally 20% of the test grade immediatly taken off since 1 person in 200 would actually manage to solve it

0 or 1

>>75620803
Ha, I didn't think about it from the unit circle perspective. Maybe that's the big idea there

>>75620856
OK, thanks

>>75621229
what books did you use, out of curiosity?
more like steward tier or apostol or god forbid rudin??

>>75621361
we dont buy books in Europe like you guys do, this is true for Portugal at least, there's really no single book for a course, a bibliography of 5/6 books is presented, usually the exercises are made by the prof(probably copied from some book), and anyway unless it's a portuguese book which the course professor wrote, which is probably hard to find online, i pirated every single one of the books i used through college...

>>75621460
>>75621361

going to every theoretical lecture, pretty much makes it so you don't have to buy books here...

>>75621460
In Greece you are given like 3-4 options, you pick one and they give it to you for free. The proffessor usually follows one textbook, so you pick that one.

>>75621540
they don't give you any book for free here, but unless you really like a physical copy , which is much better to read theory off definitely, you pirate that shit

>>75621540
for example i bought oppenheimer for my 1st signals and systems class and it cost like 100-150€? last time i bought a foreign book...

>>75621634
Some textbooks, especially ones that are written by Greeks, you can't find them online (either they don't exist or nobody has bothered to pirate them)

>>75621460
>>75621505
>>75621540
interesting. some of that happens here too. some profs just give you a free pdf, but most require you to get a book. they don't care if it is a pdf or a hard copy. the worse bastards are those who authored a book and force students to buy their book even though they may end up not using it! fucking assholes. but i have to admit most profs understand how ridiculously expensive books are and they try to make it up to you. for example they might not require you to buy the latest edition which is total scam. to fight piracy the publishers release a new edition every fucking year and just make some slight changes in exercises etc. also, some classes even to force you to buy an "online access" code to prevent you from buying a used book! so they give you a "free book" and the access code is like $100. but that's rare.

>>75621980
>also, some classes even to force you to buy an "online access" code to prevent you from buying a used book! so they give you a "free book" and the access code is like $100. but that's rare.
lol

>>75622027
their official excuse is that they provide a lot of exercises with automatic grading and also a lot of drills etc. so it is usually a freshman tier bullshit.