SQT Stupid Question Thread

I need to convert these things within the limits to fractions but I have no idea how.

I'm on my third year of math and want to study eventually a PhD in one of the fields of analysis, algebraic topology or algebraic geometry (I'll have to decide after I take these classes, which are the ones that most interest me). I have a choice of 2-3 modules this year and I'd want to know which of these would benefit me most in such a future:

Number theory (abstract algebra prereq):
>unique factorisation, ideals, euclidean rings, fields, algebraic integers, quadratic fields and integers, discriminant and integral bases, factorization of ideals, the ideal class group, units in quadratic fields

Dynamical systems (complex analysis and calc III prereq):
>Smooth ODEs: existence and uniqueness of solutions.
>Autonomous ODEs: orbits, equilibrium and periodic solutions.
>Linearisation: Hartman-Grobman, stable-manifold theorems, phase portraits for non-linear systems, stability of equilibrium.
>Flow, Fixed points: Brouwer's Theorem, periodic solutions, Poincare-Bendixson and related theorems, orbital stability.
>Hopf and other local bifurcations from equilibrium, bifurcations from periodic solutions.

Geometry (Complex, Calc III, algebra prereqs):
>The Euclidean group as group of isometries.
>Conjugacy classes and discrete subgroups.
>The affine group.
>Proof that every collineation is affine.
>Ceva and Menelaus Theorems.
>Isometries and affine transformations of R3.
>Rotations in terms of quaternions.
>The Riemann sphere, stereographic projection, and Mobius transformations.
>Inverse geometry.
>Projective transformations.
>Equivalence of various definitions of conics.
>Classification and geometrical properties of conics.
>Models of the hyperbolic plane.
>Hyperbolic transformations.
>Hyperbolic metric in terms of cross-ratio.
>Elementary results in hyperbolic geometry.

(cont)

PDEs (Calc III and real analysis prereqs):
>First order equations and characteristics.Conservation laws and their weak solutions.
>Systems of first-order equations and Riemann invariants.
>Hyperbolic systems and their weak solutions
>Classification of general second order PDEs
>Poisson,Laplace, Heat and Wave equations:existence and properties of solutions

Galois Theory (algebra prereq):
>Field Extensions: Algebraic and transcendental extensions, splitting field for a polynomial, normality, separability.
>Results from Group Theory: Normal subgroups, quotients, soluble groups, isomorphism theorems.
>Groups acting on fields: Dedekind's lemma, fixed field, Galois group of a finite extension, definition of Galois extension, fundamental theorem of Galois theory.
>Galois Group of Polynomials: Criterion for solubility in radicals, cubics, quartics, 'general polynomial', cyclotomic polynomials.
>Ruler and Compass Constructions: definition, criterion for constructability, impossibility of trisecting angle, etc.

>(a)
are you kidding me? simplify it
>(b), (c)
substitute 1/x = t, dont forget to change the limit

>trolling in the SQT thread
for what purpose

I'd go for Dynamical systems or PDE since those are easily applied to real world stuff right away...

I'm specifically going for a phd in pure maths dude, application is the least of my worries

How was that post trolling?

Do all of them pussy

if only, can only do 6 modules and i've already chosen 3-4

The answer for (a) assumes the answer is trivial, which is retarded because if it was trivial to the asker then the asker wouldn't be asking.
The answers for (b) and (c) might be possible to calculate the limit with, but they don't create a fraction.

I guess I'll take it

Substituting 1/t for x immediately creates a fraction for (b), and in (c) it's a significant step towards working out a solution. The key to building a better understanding of mathematics is to work out things on your own, making use of hints at most, rather than being spoonfed solutions.

Is IQ just a meme?

the poster's question was "how do you turn these into fractions?", not to solve them

>What is the strongest set theory you can set up,

If you take this very literally, there is no strongest set theory like this that you can set up, since you can always Godelize it to get a stronger theory.

The most obvious thing to do is just drop the powerset axiom and add your statement as an axiom, so essentially you get the theory of finite sets. You could do some other wacky things but it would likely make it difficult to talk about functions at all. Beyond that, all you need is comprehension and powerset to make the argument go through.

>substituting 1/t for x
This clears things up.
The original response said to substitute 1/x = t.
Which is the same as 1/t = x, but a lot less clear.

Why is hypochondria a thing. I'm honestly amazed at how my body likes to fuck over itself.

"A box contains 5 molecules of nitrogen diatomic gas and 15 molecules of chlorine diatomic gas. They react and form 10 molecules of product. What is the FORMULA of the product?"

Seems to be a proportion of 1 N for 3 Cl. Guessing the end formula is N2(Cl2)3 currently.

Am I retarded?

I'm about to lose my shit over this guys. Does anyone know how to do any of these?

I'm not a doctor, but the placebo effect and mind over body is real. youtube.com/watch?v=VaMjhwFE1Zw

Some unconscious part of your mind may think you are sick and subtly influencing your health. Totally not a doctor tho.

How to calculate the module of this

If you're that unfamiliar with the idea of substitution in limits, make sure you understand the other thing that user mentioned:
>dont forget to change the limit
x approaching infinity becomes t approaching 0, since
[eqn]\lim_{x\to\infty}x= \lim_{t\to 0}\frac{1}{t}[/eqn]

Yeah sure, there is not strongest, but you could e.g. ask which extensions of

en.wikipedia.org/wiki/Kripke–Platek_set_theory

you could consider (adding more and more, going towards ZFC in various ways) while keeping the countability alive.

And yeah, power set is a hindrance, but if as you say e.g. you consider one of the weaker versions of comprehension, then just having P(N) will afaik not imply this P(N) is uncountable.

I'm thinking, for the second set, since this sum 1/(2+3^n)^4 as n goes from 1 to infinity converges, so too must r^n converge. So maybe set r=0.9 or something. There's probably an exact value r is supposed to be, but I definitely don't remember how to go about doing it. I'm probably wrong. Fuck I wish I wasn't literally years away from this shit.

You get a mean when you literally take an average of recorded values from some distribution, the expectation is what your mean approaches as you take more recordings.

How much energy is required to create a shockwave that can kill all humans in a 1-mile radius.

can someone give me a function f(x) such that f'(x)>0 for all x and the function is strictly decreasing?

No, such a function does not exist.
But there is a function f strictly increasing such that for almost all x f is differentiable and it's deritive satisfies f'(x) = 0

en.wikipedia.org/wiki/Asymptote

You don't need to keep the atoms in their diatomic form. 10(NCl3)

Sorry if this was too late.

yeah, i realized i was reading the question wrong, it was asking for rate of change strictly decreasing, ive got it now

Will certain growth factor proteins and cytokines like IGF-1/IGF-2 help you grow if you ingested a small amount, say 5 µg a day?

What would seriously happen if you ingest or microdose growth factors and/or cytokines?

...

how long does Veeky Forums study for on a daily basis?

24 hours

...

Thank you Kawaii Vaginee

For physics, is there any application of fourth derivative and onward of position?

on average,like 30 mins

>he actually sits down to study
>not keeping a pocket sized master codex of all your notes that you take everywhere

i just bust that bad boy out whenever i'm standing in line or taking a dump or something. in total i get like 2 hours of study time a day with this thing but it feels like i never have to study at all.

is there an android app verson of htis?

Yes. Research it yourself.

I don't even know what "just a meme" means anymore. IQ is a real measure, it tries to measure intelligence. It isn't perfect, but it works pretty well and doesn't get caught up on "emotional intelligence" (which is just a thing to make women feel better) or education (though people with more education tend to do better, this could be because people who are more intelligent are more likely to pursue further education). Finally, IQ is a pretty good indicator of success in life, but is obviously not the be all end all. There are people with 160+ IQs who work as janitors and people with 85 IQs working as doctors.

thanks

AFAICT [math]z \notin z[/math] is allowed as a "separator" in Kripke-Platek set theory, it doesn't even have any quantifiers.

It seems like you're really looking for something like New Foundations, which doesn't allow [math]z \notin z[/math] as a formula in the first place.

I haven't started working this year desu. I just go to class, talk to people about math and try some problems every now and then.

Did she dyed her hair? Eww

Alright so here is mine.
And I know this is basic as shit but bare with me, I'm trying to make my math a bit more solid after shitty classes in high school before I begin uni and get buttfucked.

Apparently pic related is the equation for a family of lines passing through the point P, assuming both lines in parentheses pass through P. Question is: why in the name of all that is sacred is that true? I've looked on the Internet and there is no trace of a proof or decent explanation for that.
Instead, why is the equation for the family not the general equation for a line passing through a point, with the X and y of the point obviously constant in the equation and varying slope?
For example if we want to find eq. for family of lines passing through P (2 , 1), can that equation not be
y - 1 = m (x - 2)
?
Funny thing is that if you input this equation in a graph calculator and then vary m it perfectly works.

Tl;dr: explain pic related pls

I want to write a diary. A physical diary, written with pen on paper.

What is the easiest way to write such that I'm the only one who can read it, short of using a whole other language?

I'd rather not use some kind of rotational cipher or replacement symbols like the Club Penguin secret agent code, since it seems like such a tedious thing to decrypt every time I want to read.

Even a super-simple trick will do.

DAMMIT forgot pic

With a friend we used a fun trick that anyone with a bit of brain could have discovered, but no one ever did actually.

You ever used a phone that had a numerical keyboard where to every number corresponded 3 or 4 letters, and then you had to press the number an X amount of times to get a certain letter? I assume so.
Basically every letter becomes a pair of numbers. The first number is the number of the key you had to press on one such phone, and the second is the number of times you had to press is.
Take the letter c for instance. On those phones it was the third letter on the 2 key. So the cipher for c would be 23.
Decipher this as an exercise:
21747442635332

It is tricky at first, but it becomes piss easy after little time.

To "prove" that something will never end, one could simply think of the thing as a supertask of infinite steps, each half the size of the preceding one.

How would one do the opposite: Prove that something has already ended?

I remember cracking this on camp when i was 10

As said, anyone could do this if they really wanted to, but if a random family member/roommate opened a notebook and found an autistic looking array of numbers chances are they would just close the notebook and leave the room (possibly to call a doctor)

1 "asshole"?.
2. 814221625274 21626362, 43 91435353 817393 81424374 638281.
3. I use a dumbphone with a physical alphabetical numberpad anyway, I don't think this will be very hard to get used to.

Is there a term for this type of cipher? Are there computer programs/scripts that can help me decipher this stuff?

I used to do this, except I reversed the order of the numbers so 1=0, 2=9, 3=8 and so forth, since I thought it would be too simple to decipher otherwise

Oooh, perhaps I could arrange the numbers in discrete groups of 8 or something, just to surprise people.

Perhaps even use a letter to denote the number of "presses". So A would be 1, B = 2, and so on.

The people I'm trying to hide that diary from won't even fucking bother to figure it out if it's in some cipher.

I mean sure, starting there you can get as intricate as you feel the need to

Wait, why is
not(z in z)
of relevance here??

Sorry, meant [math]z \notin f(z)[/math]. But if you unravel that, it will involve some quantifiers so never mind.

en.m.wikipedia.org/wiki/Cantor's_theorem

You mean [math]z\notin f(\{z\})[/math]?

Lads is it 4 °C or 4°C? Or is that institution dependent?

The version in the pic is for a point defined by the intersection of two lines defined by implicit equations.

If the lines ax+by+c=0 and a'x+b'y+c'=0 both pass through some point, then so does every line of the form given in the pic.

The point of intersection is
x0= (b'c-bc')/(a'b-ab')
y0=-(a'c-ac')/(a'b-ab')

The gradient is:
m = -(μa'+λa)/(μb'+λb)

Substituting those into (y-y0)=m(x-x0) and simplifying gives the equation in pic.

Is buoyancy a fictitious force?

I mean centrifugal force is a real fictitious force (If I can bend English a bit in describing it that way), if you pick your reference frame properly. You can draw it as a vector on a free body diagram, even though in reality it's just inertia.

In the same way, isn't buoyancy just a product of gravity? With gravity pulling on both the object and the surrounding fluid?

I was taught to put the space between the degree symbol and the C.

Ok thank you user, I think I'm starting to get it. I'm just not familiar with the method you used to find the point of intersection. I only know how to do that with a system. Is that a simplified version of the system that I'm not identifying as such or what?

>And I know this is basic as shit but bare with me
No thanks, I'm not an exhibitionist.

no, read the damn article

Lost any ability to focus 2 years ago.
Cant do more than 2h a day.

how da FUG do I solve for this using logs?

.2153846154 - 1 = (1.02)^-n

Unknown Negative exponent and left side being subtracted by a 1.

My algebra rust as fug

Your algebra is rusty? What about your grade school arithmetic. Just fucking subract the actual goddamn numbers dude.

[math]a = 1.02^{-n}[/math]
[math]\log(a) = \log(1.02^{-n})[/math]
[math]\log(a) = -n\cdot \log(1.02)[/math]
etc

>taking log of a negative number
???

You can't take the log of a negative number though...

watch me

where does he do that?

he wrote a=1.02^(-n) and then took logs of both side

in the question the left hand side is about .2-1=-0.8 which is negative

well you're of no help.

Can someone plot the two points on a graphing calc and find the intersect? I don't have acess to one atm.

right at the part where 'a'

.2153846154 - 1 = -.79

> Is buoyancy a fictitious force?
No.

> In the same way, isn't buoyancy just a product of gravity? With gravity pulling on both the object and the surrounding fluid?
That doesn't make it fictitious. The surrounding fluid exerts an actual force on the object.

if string theory is correct, is there a possibility for free will to exist?

You'd have to use the complex log function because regular logs aren't defined for negative values.

>in the question the left hand side is about .2-1=-0.8 which is negative
google.com/search?q=log(-0.8)&ie=utf-8&oe=utf-8

>google.com/search?q=log(-0.8)&ie=utf-8&oe=utf-8
the person posted it is having basic algebra problems and i'll wager that he/she doesn't know complex numbers

Then what sort of hypothesis might you form about the problem?

either the poster or whoever assigned the question wrote something down wrong

The system can be generated by choosing any two distinct (λ,μ) pairs
λ=1,μ=0 => ax+by+c=0
λ=0,μ=1 => a'x+b'y+c'=0
Solving for x and y gives you x0 and y0

m can be found by equating coefficients
λ(ax+by+c)+μ(a'x+b'y+c') = 0
=> (λa+μa')x+(λb+μb')y+(λc+μc') = 0

(y-y0)=m(x-x0)
=> y - m.x + (m.x0-y0) = 0

Note that both equations are homogeneous so you can multiply both sides by an arbitrary factor k.
=> k.y - k.m.x + k.m.x0 - k.y0 = 0

=> (λa+μa')x+(λb+μb')y+(λc+μc') = ky-kmx+(kmx0-ky0)

(λa+μa') = -k.m
(λb+μb') = k
=> m=-(λa+μa')/(λb+μb')

>people acting like complex numbers are somehow higher mathematics
Jesus fuck it's just an i. Imagine you asked your friend how to solve 2x=3 and he told you you can't possibly be expected to solve this because no one can expect you to know what rational numbers are.

when a lunar eclipse happens on earth does a solar eclipse happens on the moon at the same time? if yes it has even been observed?

That is indeed a stupid question.

I still don't know how to decipher it.