/sqt/ - Stupid Question Thread

This thread is for questions that don't deserve their own thread.

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Other urls found in this thread:

esi2.us.es/~mbilbao/pdffiles/DiestelGT.pdf
davidsanson.com/logic/supplements/1-conditional_and_indirect_derivations.html
wolframalpha.com/input/?i=√(x-4√(x+3)+7)+√(x+4√(x+3)+7) x from -1 to 1
webqc.org/balance.php
ncatlab.org/nlab/show/Dedekind cut
ncatlab.org/nlab/show/Dedekind completion
twitter.com/SFWRedditImages

Want to prove (p->q) && (q->r) -> (p->r).

We can assume (by assumption) that (p->q) && (q->r) is true and we want to show that if p is true, then (p->r) is true.

So if we assume p is true, then looking at the assumption q must be true (otherwise if p were true and q were false then p->q would be false in the assumption).

now we have p,q are true and since q is true then r must be true since we are assuming (q->r) is true.
This essentially shows that p,q,r is true and thus shows that (p->r) must be true. -- is that correct?

What is the best book for beginner graph theory?

If you have decent mathematical maturity I recommend this.

esi2.us.es/~mbilbao/pdffiles/DiestelGT.pdf

Thanks

That worded argument is literally worth nothing. What is even the point of using logic if you are not going to argue symbolically?

Do a truth table or a proof by tautology.

Also, note that in your word argument you assume p is true and then argue based on that.

But what if p is false? You have to argue that even then it holds.

Yes.

But note that p,q, and r aren't necessarily true.
Your proof is worded informally, so I would rewrite it to have symbols line by line.

P is assumed to be true.

The way the user worded it made it pretty confusing to understand his proof, but he's basically doing two assumptions. The first being that (p->q) && (q->r) is true and the second being that p is true. An assumption is how you derive a conditional statement (P ->Q)

Did I do the proof correctly, but just worded I badly?

Can you show me a more formal proof?

Here's a page on conditional derivations which I googled. There's a format for writing proofs that makes them clear and concise. The page is on logic but this also works for mathematical proofs.

davidsanson.com/logic/supplements/1-conditional_and_indirect_derivations.html

I don't understand. I thought in an implication proof such as P->Q you assume P is true and deduce to show that if P is true then Q must be true.

This user got what my proof was.

So, is my proof correct just worded badly? Can you guys show me a more formal proof? I'm new to this.

Thanks. But can you tell me if my proof is correct? It isn't clear to me by your response. Can you also show me for this example a more formal version?

How do i become an autodidact?

Your proof is correct.

I don't know latex so this will look a little messy:

1. SHOW: (P -> Q) && (Q -> R) -> (P -> R) Conditional derivation

2. (P -> Q ) && (Q -> R) Assumption

3. SHOW: P -> R Conditional derivation

4. P Assumption

5. SHOW: R Direct derivation

6. P -> Q 2&O

7. Q -> R 2&O

8. Q 4,6>O

9.R 7,8 >O

Just got this message. Thank you, will study your proof.

Books I should study get a basic understanding of Maths and Science? No memes pls cuz I wanna get a good understanding of the subjects. My country has a shitty education system

>asking others how you can learn for yourself

What is O in your proof? My book's solution is lame, it says to prove it using truth tables.

Here is another problem (even numbered, so can't check my work).... is this also a correct proof? I am trying to get the hang of it (my book hasn't covered proofs yet, but I don't want to solve all these problems with f'ing truth tables).

PROVE:

((P OR Q) AND (~P OR R)) -> (Q OR R)

Assumption:
((P OR Q) AND (~P OR R)) is TRUE

Want to show:
(Q OR R) is TRUE from ASSUMPTION

This means:
(P OR Q) AND (~P OR R)) is TRUE

which means BOTH:

(P OR Q) , (~P OR R) is TRUE

which means

either P or Q is true, so lets arbitrarily choose P top be true, since P is TRUE, then (P OR Q) is TRUE

Similarly,

(~P OR R) is TRUE by ASSUMPTION,

~P is FALSE, so R has to be TRUE.

then (~P OR R) is TRUE.

Hence we have

P is TRUE, R is TRUE...

and this proves what we want since

(Q OR R) is TRUE since, R is TRUE.

Is this reasoning right?

Teach a man to fish...

Completely stumped on the last part. How would I set up the integral? For the surface charge density I obtained
[eqn] \sigma = \frac{qa}{2\pi(a^2 + r^2)^\frac{3}{2}} [/eqn]

Hi guys, I've been stuck on this question for a while now and I'm sure it will come up in my exam next week.

Write down a general Taylor series approximation for the function f(x) about the point x=x subscript: n that explicitly includes terms up to fifth order derivatives and a statement denoting terms beyond fifth order using big-O notation.

I can do this bit and my answer is:

[math]
f(x) = f(a) + \frac{f'(a)}{!1}(x_n - a) + \frac{f''(a)}{!2}(x_n - a) + \frac{f'''(a)}{!3}(x_n - a) + \frac{f^iv(a)}{!4}(x_n - a) + \frac{f^v(a)}{!5}(x_n - a) + O(h^n+1)
[/math]

The follow up question I have no idea how to solve.

[math]Consider a function f(x) with known values at m + 1 equally spaced points x=x_0 ; x_1 ; x_2 ; ... x_n-2 ; x_n-1 ; x_n ; x_n+1 ; x_n+1 ; x_n+2 ; .... ; x_m ;
Evaluate the series found in part a for points x = x_n-2 , x_n-1 , x_n+1 , x_n+2 to find an estimate for f(x_n-2 ) f(x_n-1 ) f(x_n+1 ) f(x_n+2 )
[/math]

I understand I'm meant to sub in x at those points into my series but there only four points given when my series up to fifth order derivatives. Am I even close to on the right track?

Those points are meant to be x at n-1 not (x at n) - 1

[eqn] PV=nRT [/eqn]

How can one find P and T with only n known?

and obviously R is known (8.314)

With a thermometer and barometer

Let us disprove the concept of Christianity by way of the Trinity.

Trinitarianism, a doctrine maintained by various sects of Christianity, runs according to the above schema, which resolves into six relations involving four entities, which may or may not be identical, or as it were equal, viz

[math] G = F \wedge G = S \wedge G = HS \wedge F \neq S \wedge S \neq HS \wedge HS \neq F [/math]

The above compound proposition, consisting of six "relatively atomic" propositions, may be phrased as T. Thus, in order for T to be the case, it must be the case that all six of the above terms are true.

But equality is a transitive relation, as expressed by one of Euclid's common notions. Thus, for example, the above entails that (for example, and other nonsense can likewise be teased out),

[math] F = S \wedge ¬(F = S) [/math]

Which is the very definition of a contradiction. Thus Christianity is false and all Christians are logically obliged to abandon their religion, though of course they won't do so in practice.

A more elaborate and tedious statement of cases can be explored about the above by means of a table, but it is clear that sufficiency alone is requisite here for this particular demonstration.

Fuck me. Disregard this, I figured it out.
with that cave-man tech.

>brainlet can't understand that God is multi-threaded
>brainlet can't understand the nuance between equivalent and equal

>>>/reddit/ is that way

I just graduated with my bachelors in mathematics, what should I do? What type of job can I even get? Will any of you hire me, I'll move anywhere!

Learn software development: git, algorithms,. data structures, some OOP language, OOP design patterns, how to write clean code.

Can someone make a short description of scientists who contributed to quantum mechanics? I'm a bit confused who did the uncertainty principle was, as well as other things.

Im going for EE but am right now at a 2 year school (just finished my first year) and am working on a gen ed degree so i get lots of electives. Any courses that arent necessarily required for EE but i might enjoy or be helpful? So far ive taken calc 1 and 2 and signed up for uni phys. Not much offered here unfortunately.

Who the hell spends four years in college without even once thinking about why they're getting this degree?
You should have been looking at careers/internships for at least a year or two now.
CS jobs will take math majors if you can code, and there are lots of various "analyst"-labeled jobs you can apply for if you have a good stats background.
If you cannot write code and your stats background is not adequate for a job you are more or less fucked and you should probably try to get into a graduate school.

Einstein, Ehrenfest, Bohr, Ladenburg, Kramers, Slater, Born, Van Vleck, Kuhn, Heisenberg, Born, Dirac, Pauli, Jordan, Schrödinger, John von Neumann, Dyson, Fermi, Feynman, Foley, Klein, Oppenheimer, Weisskopf, Schwinger, Kusch, Lamb, Nordsieck, Retherford, Källen, Bethe, Bloch, Tomonaga, Kroll, Karplus, Wigner, and Villars.

College isn't job training.

HOW THE FUCK DO I FIND IT FFS?!

Linear Algebra, General Chemistry 1&2 + lab

Can anyone help me understand how exactly electron orbitals relate to stability? I know it's like sophomore chemistry but it's always been something I never could fully understand.

√(48+80+120cos(∡KMP))

what do you do here?

HOW FFS?!

you begin with -1

I don't fucking get it. How do you "build them up"?

wolframalpha.com/input/?i=√(x-4√(x+3)+7)+√(x+4√(x+3)+7) x from -1 to 1

law of cosines

like I said
if -1

2

there's nothing fucking there

Well the answer is 4, so... WTF DO I DO?!

> | x + y | = 1

HOW THE FUCK DO I REWRITE IT SO IT'S A NORMAL EQUATION WHERE Y OR X ARE EQUALED OUT?!

(sqrt(x-4*sqrt(x+3)+7)+sqrt(x+4*sqrt(x+3)+7))^2
=(x-4*sqrt(x+3)+7)+(x+4*sqrt(x+3)+7)+2*sqrt((x-4*sqrt(x+3)+7)*(x+4*sqrt(x+3)+7))
=(x-4*sqrt(x+3)+7)+(x+4*sqrt(x+3)+7)+2*sqrt((x+7)^2-16*(x+3))
=(x-4*sqrt(x+3)+7)+(x+4*sqrt(x+3)+7)+2*sqrt(x+14x+49-16*(x+3))
=(x-4*sqrt(x+3)+7)+(x+4*sqrt(x+3)+7)+2*sqrt(x-2*x+1)
=(x-4*sqrt(x+3)+7)+(x+4*sqrt(x+3)+7)+2*sqrt((x-1)^2)
if x>1
=(x-4*sqrt(x+3)+7)+(x+4*sqrt(x+3)+7)+2*(x-1)
=(x+7)+(x+7)+2*(x-1)
=4*x+12
if x

y=±(1-|x|)

>(sqrt(x-4*sqrt(x+3)+7)+sqrt(x+4*sqrt(x+3)+7))^2
Where the fuck did you get this?

>Thus it's 4 if x1.
It's IN-BETWEEN ffs.

The answer is 4. HOW?

>Where the fuck did you get this?

I squared it and then square-rooted it in the end.

x+y = ±1
y = ±1-x

take me thru pls

>That worded argument is literally worth nothing. What is even the point of using logic if you are not going to argue symbolically?

Have you literally never had a math class?

In geometrical progression (bn) tenth member is b10 = -18, and the thirteenth member b13 = 164. Search for:

1) the arithmetic average of the first five members of this progression;
2) the median sample consisting of the first seven members of this progression.

Answer is the difference between 1 and 2.

WHY THE FUCK IS IT 21 AND NOT 39/5 FFS?!

HOW DO I EVEN CHECK IT IN FUCKING WOLFRAM?

THOSE JEWS GO ABOVE AND BEYOND TO LIMIT WHAT YOU CAN DO WITHOUT GIVING OUT CASH.

How to become risk analyst? I mean, what books should I study? Take into account I have a math degree.

HOW THE FUCK DO YOU FIND IT FFS? I transform the upper one to get x + 3y = 2, then add the two equations and get one solution. BUT HOW DO YOU GET ANOTHER FFS?! WHY IS THERE EVEN ANOTHER ONE?!

b_n= a*r^(n-1)
r=cuberoot(164/-18)
a = 164/r^12
average = a(r^5-1)/(r-1)/5
median = a*r^3

average - median = 0.279627009089994

Looks like youll get 4 answers (2 for each) but only 2 answers (1 for each) will be correct. But once you get your first answer, just plug it in to get the second.

x=3y+2
(3y+2)^1 + 6(3y+2)y + 9y^2 = 16

solve for y

So I'm in R experimenting with some sequences, and I want to find out if two sequences converge to 0 at the same rate, specifically these sequences are:


[math]\displaystyle s_n = \frac{1}{n}\sum_{k=1}^n \frac{1}{k} [/math]

and

[math]\displaystyle t_n = \sum_{k=1}^n \sqrt{\frac{k}{n}} \left(\sqrt{\frac{k}{n}} - \sqrt{\frac{k-1}{n}} \right) [/math]

What is the best way to investigate this graphically? This specific example, indeed [math]t_n \sim s_n[/math], but how can I visually see it? I tried plotting [math]t_n [/math] against [math]s_n[/math], and I think it looks it clumps to a straight line but I can't be sure.

What are some better ways?

reposting from last thread:
can anyone who does mechanics or something similar help me understand pic related.
should the indexes on [math] \Pi_1,\Pi_2 [/math] be swapped and why is the final solution not [math] P=\sqrt{\frac{D}{g}F(θ)} [/math]?

why do you keep autisticially posting those reddit pictures

by studying the sequence you obtain from forming the difference of the two sequences?

build a man a fire, keep him warm for the night
set a man on fire, keep him warm the rest of his life

>Let us disprove the concept of Christianity by way of the Trinity.
>Trinitarianism, a doctrine maintained by various sects of Christianity

You CANT disprove something by taking a special case and showing that it is false for that special case.

And you are the """"""""logical"""""""" people (who dont understand logical) who tell Christians that their faith is illogical.

...except this is an over-simplification of a very specific and particular interpretation of the trinity in Christianity. By the way, your entire argument falls apart when you view the relationship between the persons of the trinity as a relationship of intersections (or subsumations), a perhaps more accurate description of the trinity.

i think im missing something really simple here but i dont understand how to get to 12.6cm

Daniel Tosh makes a joke about an inmate getting stabbed 682 times. He proposes that 2 stabs per second is doable and according to his math that would take "5 minutes and 40ish seconds." I did the math and got 6 minutes and 8 seconds. What is the correct answer?

Not well versed in fluid dynamics(?) or what I'm supposed to do

2 stabs per seconds => 341 seconds of stabbing => 341/60 stabs per minute => 5,6 stabs per minute => 5 minute 40 secs

>the father is an element of God
>the son is an element of God
>the holy spirit is an element of God
>but the father isn't the son isn't the holy spirit?

Thought by doing 341/60 would just convert the seconds to minutes. If he stabs the inmate 5 times per minute wouldn't 5 minutes=25 stabs?

341/60= 5.68 minutes=5 minutes and 40.8 seconds. You can just estimate it to 5 minutes and 41 seconds. I unreasonably thought 5.68 meant 5 minutes and 68 seconds and just convert it to 6 minutes and 8 seconds. My bad lol

>It's IN-BETWEEN ffs.

For all x

God is an equivalence class consisting of father, son, and holy spirit.
Propositions true of God are true of any of the elements of the class.
The elements are not identical, but they are equivalent modulo God.

If we detected a cataclysm-imminent asteroid on a direct collision course with earth, when would it be detected and how would we attempt to prevent the impact?

How do I get an antiderivative to give the proper integral values for negative values of x?

An urn contains n balls numbered 1, 2, 4, 8, etc. up to 2^(n-1) where n > 1. If a person selects 1 ball from the urn, then replaces it and selects a second ball, what is the expected value of the sum of the ball's numbers?

Ok sci is even worth to do all Stewart exercises per chapter or I should keep doing odds only?

Chemistry - Stoichiometry

>1 metric ton of ore yields 12 kg of CuFeS2
>6 million ton ore/year is processed to extract copper
So.. 6 000 000 ton x 0.012 = 72000 ton CuFeS2/year is processed..
>How large of a mass is extracted from CuFeS2 every year?

What the hell do I do know?

More of an uni etiquette thing - I have a genuine question I want to ask one my profs, that I should've asked months ago. The exam for his course is a couple of days away, so I don't think it would be appropriate to send an email now, and neither would it be for the rest of the finals period. And neither it would be during the summer vacation("hey, remember the thing I was supposed to look up half a year ago? Got a question about it"). What do

webqc.org/balance.php

CuFes2 --> Cu + FeS2
Has a 1:1:1 mole ratio

When you get the amount of substance for CuFeS2 you just have to: amount of substance x molar mass of copper.

It looks like it'll be unruly numbers though.

Just ask

Hey guys I got a homework question on sequences

an = n*log(n) - n*log(np+2)

Have to find the values for p>0 for which an converges as n --> infinity, then evaluate the limit in terms of p.

I got up to this

log(1/p) * lim (n), but how would you proceed further?

>n*log(n) - n*log(np+2)

n*log(n) - n*log(n(p+2/n))
-n*log(p+2/n)
-log( ( p+2/n)^n )

if p == 1
-log( (1+2/n)^n )
-log(e^2) = -2

if p infinity

if p>1
then for all n, (p+2/n) >= p
so (p+2/n)^n >= p^n -> infinity and -log(infinity) = -infinity

Pythagoreian theorem for each of the three triangles. (KP) = 32

Two times the mean of one draw

Which is the proper order of quantifiers to state the Cut Property?

If [math]A[/math] and [math]B[/math] are nonempty, disjoint sets with [math]A\cup B=\mathbb{R}[/math] and [math]a

Why is it taboo to say black people commit more crime than any other race despite being just the 13% of the population?

Think about what the second term means. It says that a c exists with is greater then all a and less then all b.

That really doesnt make much sense.

I mean... it's a valid property taken from my book so the property itself is not invalid. It's because a < b for all a and b.

I have calc next year, had some high school plug and chug 2 years ago. The teaching was pretty bad, as I'm only now discovering words like polynomial, coefficient, etc.
Is there a book or material for someone who can basically do all the "solve for x" questions, but fails to understand what they're actually doing/what anything means?

Also, why does deriving a sinusoidal function 4 times provide the same sinusoidal function?
Is there a deeper meaning to it and is it related to complex numbers?

I understand that but, if c is greater then all a it is not in A and if c is less the all b it is not in B.

So we have a real number neither in A nor in B...

The Cut Property of the real numbers is the following. If A and B are nonmempty, disjoint
sets with A ∪ B = R and a < b for all a ∈ A and b ∈ B, then there exists c ∈ R such that x ≤ c
whenever x ∈ A and x ≥c whenever x ∈B.

use dedkind cuts to see what goes on, instead on relying on dubious definition of real numers
ncatlab.org/nlab/show/Dedekind cut
ncatlab.org/nlab/show/Dedekind completion

I misstated it. The book says: x≤c whenever x∈A and x≥c whenever x∈B

Waaait a minute. My interpretation of this property is that there is one and only one "c" that "sits between" A and B on the number line, splitting them. Could be in A or B but not both. Is that what this says or am I misinterpreting it?

do breast implants affect titty milk?