SQT

New stupid questions thread.

Can someone explain why
[math] \cap_{a\in J} A_a\ \not\subseteq\ \cap_{a\in I} A_a\quad\textrm{where}\quad J\neq \varnothing,\ J\subseteq I[/math]
An example would be helpful.

Other urls found in this thread:

youtube.com/watch?v=oBb3ZjVpmXs&list=PLA7857619F91267C0
en.wikipedia.org/wiki/Hydraulic_analogy
en.wikipedia.org/wiki/Jewish_population_by_country
en.wikipedia.org/wiki/Geometric_series
twitter.com/SFWRedditGifs

is this an example?

A_1={a,b}
A_2={b,c}
A_3={c,d}
I={1,2,3}
J={1,2}

then left hand side is {b}
right hand side is empty
so no inclusion

thanks, I was just being dumb

So as soon as you add another set to your indeces, you introduce the possibility of it being disjoint with one of the others?

Just took a calculus I class and physics I class (algebra). I didn't really "understand" physics I and just plugged and chugged which got me a 90. I want to relearn physics I but with calculus. what's a good book and video series?
I found this: youtube.com/watch?v=oBb3ZjVpmXs&list=PLA7857619F91267C0 but there's no electricity and magnetism

Dunno man, just go to Kahn Academy or something. It seems like a waste to get a book just to remember basic physics. Then get a book on something you want to photos on, Landau has them all, but I don't like his notation.

Phocus*

so my education on maths more or less ended with linear algebra in secondary school, and now im trying to get to grips with calculus on my own. can someone please explain to me what the fuck the rules are for variable naming in calculus? because my understanding of things is generally that ab=a*b, and yet i see ab being used as a single variable name in calculus.

What did he mean by this

What is the best way to find top professors in a given field of study? Google scholar? Researchgate? In EE and specifically photonics/optics, RF/Electromagnetics, image processing/DSP fields

preferably I would just download the book.

can one of you mongs answer this pleaseee? Have asked it for the past 4 sqt

You should probably get Calc 3 before taking a physics book. Before that, review physics with your high school book or online vids.

J is a subset of I, so you perform fewer intersections and end up with a set that's always at least as big as the intersection over I

more generally if J and I are countable, the cardinality of the intersection of a sequence of sets is a decreasing monotone function.

How do I learn about organic chemistry of pharmacology to better understand amphetamines?

Any books or resources for thos without a background in chem?

I have an inequality here in pic related. Perhaps someone could help me with it?

It is from a problem set and the problem below and above it are pretty easy, so I assume this problem isn't too hard but I just don't see an opening. I have no idea with how to start.

Making a webapp just for shits that generates primes. I implemented the sieves of eratosthenes, sundaram, and atkins. Any other ones, or ideas of other shit I should put in? I'm thinking a graphing utility to time them would be neato

Maybe write the numbers as

A =Σαk*10^k, B=Σβk*10^k
Where αk, βk are their digits

Seems useful but unsure where to go from there...

Yeah, that's the obvious start (I think). But after that I see no identity to apply.

How does the eletrons of a current pass through the battery if a battery is basically just two eletrically polarized compartments which are separated from each other?

I am smart enough to take a dual major in Physics and Math in just 4 years, but I want to get into the tech industry, because one day I want to work in Japan and IT is the only way in if I don't want to become an eigo-sensei. The Japanese are extremely conservative when it comes to work shit, they look solely for CS undergrads for jobs in software engineering and that kind of stuff. What does Veeky Forums think I should do? I want to be proud of myself and study cool stuff, but I also want to move to Japan. Maybe a CS degree with dual minors in Math and Physics?

Could I become a climate scientist via online courses (with certifications and whatnot)? There's a lot of official stuff online that offers certifications from accredited universities and colleges. I can't afford to go to college and this is way more affordable.

Why the voltage of a circuit isn't equal in all parts of the circuit just like how the hydraulic pressure is in a pipework circuit?

Why does the eletric pressure of a current drop after each resistor in the circuit?

when you say [math]ab[/math], do you mean [math]\text{d}x[/math]? Because [math]\text{d}x[/math] is an infinitesimal change in [math]x[/math], and can be manipulated as a single variable. Otherwise your book is pulling some retarded shit that I've never seen elsewhere.

pic related, dt and dx. dt and ds are defined as scalars here, i just dont quite get the rules in order to make complete sense of this expression.

This is shitty notation. Get some other book.

what book should i read? i have a poor grasp on math, but i see this notation being used to describe derivatives all the time

I've no idea since my background is pure math. Why are you studying calculus after all?

I began calculus with Apostol, you should try it to see if you can manage. Spivak is also good. Neither will pull shit like this, if the author doesn't even define expressions properly just throw the book in the trash, calculus is already "hard" as far as baby math goes.

to better get to grips with neural nets, which require i understand derivatives

Where, exactly, does one find interesting, juicy mathematics problems to sink their teeth into? A good textbook will obviously have some. Anywhere else?

Please help

I was checking my answers for calc in wolfram and one answer was wildly off. Eventually I figured out it's because wolfram and I disagree on the derivative of sin(x + pi/3)
All of my knowledge says it should just be cos(x + pi/3), but picrelated is what wolfram is saying.
I'm sure as hell not going to pay them just to understand this answer, so can anyone explain what's going on?

What a strange notation. It looks to me like you're dealing with the formal definition of a derivative, and the notation is usually (f(x+h) - f(x))/h, at least in my experience.

I'm doing a Dual Degree in Mathematics and Computer Science, and going to finish a year early. You could do the same but push a physics minor in there to make it 4 years

Having finished your BSc you may apply for masters in Japan. I just want to warn you that one may find software engineering overly boring.

en.wikipedia.org/wiki/Hydraulic_analogy
Answer: you're wrong about hydraulics, there are
pressure differences across obstructions in pipes.

pretty much, i just need a good explanation that works for someone whos really rusty on their maths

I'm learning formal logic, for some reason the following doesn't seem correct:

"Rewrite the statement:
Everybody trusts somebody in formal language. "

Let, X = people, and
Y = a person
P(x, y) = ∀ x, ∃ y such that x trusts y.

This just doesn't seem as formal as the examples in my text.

Let P(x) be the predicate “-10 < x < 10” with domain Z (set of all positive integers. Find the truth set of p(x).

=

{-9, -8, -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9}

Or is it not inclusive of 0?

Is math related to science? If so, how so?

How do I stop being a brainlet?

What's the name of this function?

Grosine

Is time a requirement for 3d objects to move through space or does the movement of 3d objects create time?

Spacetime is one. So yes

X should be a person as well

Statistics question. I have a data set that seems to follow a normal distribution. I want to find out if there are anomalies (dont know the word for this, reproducible outliers?), but I also want to be able to reason about this myself. Are there any recommended online courses (Ive a CS masters but little training in statistics) that'll get me to the level of being able to do this in a reasonable timespan?

Or a book I could learn.

>reproducible outliers

Outliers only make sense in the context of a sample, not the actual distribution. If you're looking for outliers in a sample from a normal distribution, use Grubb's test.

What if you have a graph that looks like the bell curve but with a narrow 2nd top somewhere that is reproducible in new data sets? Is there a word for that?

Basically, h (or dt in this case) is the Δx of when you're figuring out a secant line. You take the limit as Δx approaches 0, thus getting the slope of the tangent line.
The formal definition of a derivative is really just taking the slope of the line that you're generating there.
It's basically the old rise/run to find slope that you would use in early algebra. You can think of it as
x = x1; x+h = x2
f(x) = y1; f(x+h) = y2;
Which makes the formula into (y2 - y1)/(x2 - x1) but obviously x2 is x+h, so x+h-x is just h.

Is this helping? I don't really know if I'm making sense, I'm kind of tired.

m8 i have no fucking clue about half of what you said, my maths education ended at 16 and that was 7 years ago now

in any university?
Ivy League

I reccomend you learn R
>r-tutor.com
give all the distributions a read
keep in mind this is only for a quick start, I highly reccommend a book

for book, I like Ross (libgen)

not true in general since one might have J = I

Will
calculus 1
Intro to Chem (toughest expert on campus, but also took this in high school pretty much)
And cop2000 ( intro to programming)
With a 30 hour/week job be detrimental to my learning and success ?

I did just have the first two but through on the cop2000

Do any chess engines take either
>game time remaining
>previous moves (in particular blunders)
into account?

How do population dynamics work?

I want to estimate the Jewish population in 2017 supposing the Holocaust never happened

en.wikipedia.org/wiki/Jewish_population_by_country
>In 1939, the core Jewish population reached its historical peak of 17 million
>Due to the Holocaust, the number was reduced to 11 million in 1945.
>The world's core Jewish population was estimated at 14.31 million (around 70% of the world's "enlarged" Jewish population) in early 2015.

I asked a 19 year old girl if she had sex before and she said her body "isn't ready" for sex (probably relevant: she's extremely skinny). What did she mean by this?

It means she doesn't want to fuck you.

So any professor at a high ranking EE school should be top tier? Just wondering because I am applying to top 5,10 schools for grad school and have also been told that a top professor matters more. Just wondering if I could find like maybe top 20,40 schools that have a really good professor as a safety school.

Have some pharmaceuticals done more harm than good (thinking of fentanyl)?

Sure, lots of them. Most recreational drugs are also prescription medicines. And many medicines have ended up being withdrawn (or at least restricted) after the side effects became better known (e.g. Thalidomide).

How do I make the filesize of a 100x100 jaypeg file as large as possible?

Is it possible to re-learn math and physics within a month and a half?
what would it take to do so?
not necessarily 100%

So that it wont compress easily, lots of different colors, lots oft irregular patterns

Is it possible to add metadata to a jpg? If so, that'd be another thing one could try to abuse.

cos(x+π/3)-sin(1/6(π-6x))=0

When do I know whether the uncertainty is greater or equal to either the reduced planck constant or the reduced planck constant over 2

How do i answer question 1?

I'm starting my first semester of college in about a month, taking linear algebra. I have a TI-84 I used in high school calculus. Is there any reason I'd want a newer calculator, either new features or just increased efficiency? Or is the calculator not all that relevant?

X=0 Y=20
A square will be bigger than simple addition

Don't bother wasting money if you already have one, they have all the same features but just look more fancy with all those colours

I mean, the CX-CAS can do algebra and calculus for you. So you could get that if your professors would be okay with you using it.
Plus, it also intelligently automatically fills in parenthesis, which is a godsend.

>using a calculator

Is it actually possible to definitively crack one of the CIA numbers stations without one of their pre-shared keys? Like could you get to the point where you have a solution and know for a fact that it is the right message?

>set of all positive integers
so I'd say it doesn't include 0, and it also doesn't include the negatives. so just 1 thru 9

Think about a straight line.
It has the form
y = mx + b where m is the slope and b is the y intercept. On a line, it is easy to see what the slope is. It is m, as just stated. Furthermore, the slope is the same no matter what point you test it at.

Now consider a function like
y = x^2
In some places, the slope is negative. In other places, it is positive, and at one point in particular, the slope is 0.

In this case, the slope is not constant, like it is with the line, but instead varies throughout the function. All development of calculus studies how the slope of a function is related to the function. Instead of getting a number, you usually get another function.

Going back to our examples, in calculus the slope is defined as dy/dx. You might also see it written as y' or y with a dot over it. They all mean the same thing.

You don't have to worry about the definition of an integral or derivative until you get to analysis, as all previous explanations such as your text and this post are extreme simplifications. But unless you study pure math or need to write a program that does calculus for you, it doesn't matter. So just learn the rules for derivatives and integrals.

For a line, dy/dx = m if you follow the rules, which is what everyone learns in grades cool without knowing calculus.

For the parabola, dy/dx = 2x. When x is negative, the slope is too. When x is 0 the slope is 0. When x is positive, so is the slope. Look at a graph of a parabola and it is apparent.

Finally, an integral is essentially the inverse of a derivative. Just like adding/subtracting or multiply/divide or exponents and logarithms. Again, this is very basic and 99% of stem majors don't even know why they do it, so don't sweat it. Just learn the techniques.

I'm on chapter 3 of this and so far have been having trouble solving most of the proof exercises on my own, giving each at most 30 minutes before giving in if I can't figure it out (assuming that's about what the author expects of the average reader).

Should I just give up on the thought of any STEM degree that isn't plug and chug? I just wanted the math education that I never had before starting college, not these feelings of worthlessness.

What's the best way to learn multiplication tables?

I skipped 3th-5th grade due to moving a new country with a foreign language (fuck off /pol/, it was a white first world country to another white first world country, seriously fuck off) and so the moment I got back into school calculators were already in use.

Retard here.

Can a change be physical and chemical at the same time? In other words, what does the term ''Physical-chemical change'' actually imply?

Is an explosion a physical or chemical change? (ex. the exploding of nitroglycerine)
Help is appreciated.

Resolution Logic

I have 3 claims.
C1 = { ~S(x), ~SCIS(x), CS(x), IT(x) }
C2 = { ~S(a), ~SCIS(a), ~CS(a) }
C3 = { ~S(a), ~SCIS(a), ~IT(a) }

There's no way to find the empty clause is there...? (i.e. the following argument is false)

I got the clauses by the argument:
“Every student in the SCIS is a CS student or an IT student.
Therefore there is a student in the SCIS being a CS student or an IT student”

I did formalization, skolemization, negated the conclusion, and then got the clauses I got. I don't see anyway to reach an empty clause by resolution. Did I get the correct conclusion?

As a kid I used flashcards. 12x12 times table is a good standard. Learn 1 row, then add another row to the deck and continue. You find patterns and tricks as well. Like for 9s theres a fingers trick you can google to learn. You also eventually get faster at just adding a number over and over in your head to find the solution once you know the basic multiples.

Proofs are hard at the beginning, just keep at it.

Consider reciting them out loud like "7, 14, 21..." but also as "1 times 7 is 7, 2 times 7 is 14, ..." That's what I was required to do in school.
It's an easy skill to practice since you can do it while walking, sitting, driving, etc.

Will smoking weed permanently hinder my Veeky Forums abilities? If so, how often can I get away with it without worrying?

Yes. 0 times.
If you care about your brain don't take substances who heavily interact with your brain.

Propositional Logic/First Order Logic

“Every student in the SCIS is a CS student or an IT student.
Therefore there is a student in the SCIS being a CS student or an IT student”

S(x): x is a student;
SCIS(x): x is in SCIS;
CS(x): x is CS student;
IT(x): x is an IT student

1st sentence:
Ax( S(x) SCIS(x) --> CS(x) IT(x) )

2nd sentence:
Ex( S(x) SCIS(x) (CS(x) IT(x)) )

Is this correct?

Can I just use integration rules instead of Riemann sums? I'm working through a calc book and this chapter wants to integrate using Riemann sums. Seems kinda of pointless since no one uses it anymore

Your sentence is essentially of the form [math]\forall x \phi \implies \exists x \phi[/math], which follows from universal instantiation + existential generalization, [math]assuming that the domain of discourse is nonempty[/math].

Otherwise, you couldn't rule out the possibility that there are no students in the SCIS at all, in which case the premise
>“Every student in the SCIS is a CS student or an IT student.
would be vacuously true but the conclusion would be false (since no students exist).

Though once you grant that assumption of existence, the logic becomes valid and everything else you've written is correct.
(That said, you seem to have a predicate SCIS(x) so I'm not sure what exactly your domain of discourse is.)

Suppose a regular tetrahedron is inscribed in a sphere. Now suppose a line is drawn connecting any two points in the shortest distance possible around the surface of tge sphere. What percentage of the circumference of the sphere would this line be?

>expecting math to be easy
You gotta let go of some of your pride, kiddo.

Everything is physical. :^)

one third

1) How do I reduce 5 * (2^n ) + 3 * (2^n) - 5 -- the solution has 2^n+3 - 5 but I don't remember the algebra rules to reduce it to this.

2) Does [Sum k=1 to n-1 2^k ] = (2^n - 1)/(2-1)? It looks like it does based off a few examples I've seen.

>How do I reduce 5 * (2^n ) + 3 * (2^n) - 5
a*b^n+c*b^n
= (a+c)b^n

> Does [Sum k=1 to n-1 2^k ] = (2^n - 1)/(2-1)
en.wikipedia.org/wiki/Geometric_series

Thanks on 1)

It still isn't clear if my generalzation is correct on 2)

I know sum k=0 to n a^k = a^n+1 - 1/ a- 1

but is [Sum k=1 to n-1 2^k ] = (2^n - 1)/(2-1) correct? A recurrence relation proof I am doing relies on this guess of mine.

Also,

5 * (2^n ) + 3 * (2^n) - 5 = 2^3 * 2^n = 2^n(n+3) - 4 is that what happens?

2^3 * 2^n - 5 = 2^(n+3) - 5 ******