## Search found 73 matches

Mon Oct 25, 2010 5:16 am UTC
Forum: Mathematics
Topic: Quintic Equations
Replies: 12
Views: 4444

### Re: Quintic Equations

Questions such as this and many other interesting ones are addressed by Galois theory. That is the summary of what I know about Galois theory, that and it involves something with complex conjugates.
Sun Aug 15, 2010 11:10 pm UTC
Forum: Mathematics
Topic: Homework Help (Distributing into a fraction) Solved
Replies: 6
Views: 1578

### Re: Homework Help (Distributing into a fraction)

-(x^2-1)/(x+4) = (1-x^2)/(x+4) = (x^2-1)/(-x-4)
Tue Jul 27, 2010 8:51 am UTC
Forum: Mathematics
Topic: Exponents with Trigonometric Functions/Logs/etc.
Replies: 41
Views: 5386

### Re: Exponents with Trigonometric Functions/Logs/etc.

"Just cause." It's one of the irritating ambiguities of popular mathematical notation.

Another is when people say 'log' they frequently mean base e, base 10 or sometimes even base 2, depending on who you talk to.
Mon Jul 19, 2010 7:33 am UTC
Forum: Science
Topic: I'm going to be a Physics Major...
Replies: 18
Views: 4811

### Re: I'm going to be a Physics Major...

Stewart as a math book is pretty terrible, but I suspect most students in engineering and science based calculus classes have to endure it. For extra fun, pick of Spivak and read it on the side (or just read it by itself, no difference).
Fri Jul 16, 2010 8:08 am UTC
Forum: Mathematics
Topic: Usages of calculus.
Replies: 16
Views: 2527

### Re: Usages of calculus.

There are many theoretical applications of derivatives and integrals. Proof that pi is irrational: http://www.lrz.de/~hr/numb/pi-irr.html The proof that e is irrational (the one I know anyway) relies on Taylor series, which relies on derivatives and integrals. The proofs I know of pi's and e's trans...
Mon Jul 05, 2010 7:02 am UTC
Forum: School
Topic: Post your 2010 AP/IB Scores!
Replies: 47
Views: 7146

### Re: Post your 2010 AP/IB Scores!

CollegeBoard loves to steal as much of your money as possible.

Also I only took econ this year so I'll just wait for them to mail it to me. Not sure why I even took econ anyway.
Fri Jun 11, 2010 5:51 pm UTC
Forum: Mathematics
Topic: Two derivatives for a conic?
Replies: 4
Views: 1051

### Re: Two derivatives for a conic?

Think about it. If you have the elliptic curve x^2/4 + y^2/9 = 1, and you take the x coordinate to be, say, .5, there are two points on the curve that fall on the vertical line x = .5. Granted, this ellipse is symmetrical about the x axis, so the derivatives will just be negatives of one another at ...
Tue May 25, 2010 3:04 am UTC
Forum: Science
Topic: ∆H (Change in Enthalpy) for photosynthesis. (Use Hess's Law)
Replies: 11
Views: 11226

### Re: ∆H (Change in Enthalpy) for photosynthesis. (Use Hess's

Hess' law is intuitive. If it doesn't strike you as so, think about why it is until it does. Make analogies involving putting things in a bag. You'll find it easier to remember when you have that kind of firm grasp on it. If you have to look up the equation for Hess' law, you're not thinking about i...
Tue May 25, 2010 2:58 am UTC
Forum: Mathematics
Topic: Calculus question
Replies: 10
Views: 1491

### Re: Calculus question

It's all about definitions. We define the symbol a^x = e^(x ln(a)). e^x is defined as exp(x), which is defined as the inverse of ln(x), which is defined as the integral from 1 to x of dt/t. Using this definition, we have \frac{d}{dx} x^{a} = \frac{d}{dx} e^{a ln(x)} = \frac{a}{x} e^{a ln(...
Tue May 25, 2010 2:50 am UTC
Forum: Mathematics
Replies: 9
Views: 1649

### Re: Question about infinite series

I am in Calculus BC right now (or II, or whatever you want to call it it. High school calculus course part 2), and we learned about infinite series and sums and stuff earlier in the year, and I was wondering if the specific property I'm looking at has a name. Let me demonstrate. From what I can tel...
Tue May 25, 2010 2:43 am UTC
Forum: Mathematics
Topic: Quick Question on Similar Integrals
Replies: 7
Views: 1341

### Re: Quick Question on Similar Integrals

For some reason a lot of high school calculus classes seem to teach u-substitution without actually teaching what it really means. Consider the following: Define the function F such that F'(x) = f(x). \int_{g(a)}^{g(b)} f(x) dx = F(g(b)) - F(g(a)&#...
Sat Apr 03, 2010 11:05 pm UTC
Forum: School
Topic: Cornell
Replies: 2
Views: 1219

### Re: Cornell

I was accepted December 10. Hope to see you in April ^_^
Sun Jan 24, 2010 7:49 am UTC
Forum: Mathematics
Topic: Dont make fun...I need help to solve this
Replies: 16
Views: 2019

### Re: Dont make fun...I need help to solve this

I'm pretty sure undergraduate math classes have homework.
Sun Jan 24, 2010 7:45 am UTC
Forum: Mathematics
Topic: Antiderivative and Area Help
Replies: 3
Views: 1304

### Re: Antiderivative and Area Help

I remember the proof I read in Spivak's "Calculus" going something like this: Let f be integrable on [a,b] and define F(x) = \int_{a}^{x} f(x) dx For c in (a,b), we have F'(c) = \lim_{h->0} \frac{F(c+h)-F(c)}{h} If h > 0, then F(c+h)-F...
Wed Dec 23, 2009 6:11 am UTC
Forum: Mathematics
Topic: Calculus Applications Book
Replies: 9
Views: 1615

### Re: Calculus Applications Book

Depending on how seriously you want to understand calculus, after you've mastered the book on integration and differentiation you may consider studying Real Analysis. Introductory Real Analysis is basically the theory behind calculus (rigorous proofs of all the results in your first calc book, etc....
Sat Dec 12, 2009 8:39 pm UTC
Forum: Mathematics
Topic: Simple proof for a removable discontinuity
Replies: 9
Views: 2291

### Re: Simple proof for a removable discontinuity

The limit of that function as x tends towards zero doesn't exist. Look at the graph: http://www2.wolframalpha.com/Calculate/MSP/MSP345198d97f336b3gb830000222051bid1h49hg2?MSPStoreType=image/gif&s=22 As x approaches zero from the right, the limit is 0, but as it approaches zero from the left...
Mon Dec 07, 2009 3:24 am UTC
Forum: Mathematics
Topic: Putnam
Replies: 33
Views: 3059

### Re: Putnam

This post on Reddit has the problems on the latest one (according to them at least) in case anyone needs inspiration to start discussing solutions.
Wed Oct 28, 2009 7:31 pm UTC
Forum: Mathematics
Topic: Is Pi Infinitely Long?
Replies: 57
Views: 5775

### Re: Is Pi Infinitely Long?

If a decimal number d terminates, it is clearly rational, because there exists a natural number n high enough such that d*10^n is an integer, and d=d*10^n / 10^n. However... http://en.wikipedia.org/wiki/Proof_that_%CF%80_is_irrational The proof is kind of advanced and involves calculus, but if you h...
Sat Sep 05, 2009 7:30 am UTC
Forum: School
Topic: AP U.S. History
Replies: 27
Views: 2710

### Re: AP U.S. History

At my school that's a two year class. I got B+'s both years, although my teachers were really intense and I pulled off a 5 on the exam.
Tue Aug 18, 2009 5:12 am UTC
Forum: Mathematics
Topic: Algebra 2?
Replies: 21
Views: 3061

### Re: Algebra 2?

The natural logarithm function, ln(x), is the inverse of the exponential function, exp(x) = e^x.

Similarly, the function log(x) is the inverse of the function 10^x.

For example, if you have 10^x = 1000, then x = log(1000) = 3.
Tue Aug 18, 2009 5:04 am UTC
Forum: Mathematics
Topic: Inverse Functions help!
Replies: 19
Views: 2103

### Re: Inverse Functions help!

Sun Aug 16, 2009 9:15 am UTC
Forum: Music
Topic: Worst song lyrics
Replies: 332
Views: 60793

### Re: Worst song lyrics

Ovaltine, mustard, half a pound of ground beef apples, Lays chips, and a loaf of wheat bread orange juice and mayonaise, low-fat spam and strawberries Oatmeal, Pepsi, Skippy beats Jif again Ice cream, margarine, knock-off store brand cheerios OREOS ON SALE TODAY WHAT ELSE DO I HAVE TO SAY This made...
Fri Aug 14, 2009 6:53 am UTC
Forum: School
Topic: Do I have a chance at Caltech?
Replies: 13
Views: 2356

### Re: Do I have a chance at Caltech?

The unfortunate answer is, goddamned if I know. I know four people who took BC calculus as sophomores and got 5s. Two are going to Princeton, and two are going to Rutgers. What does that mean? It means that, while that's certainly nice to have, it doesn't mean very much. What stands out much more to...
Sun May 10, 2009 5:40 am UTC
Forum: Mathematics
Topic: AP Calc BC 2009
Replies: 17
Views: 2818

### Re: AP Calc BC 2009

Question #6 was easy. :P It's certainly valid material. They aren't asking for any significant independent breakthroughs in calculus to be made, but they are testing your fluid intelligence to an extent. Sure, nobody ever told either of us how to decide if there were inflection points for a graph of...
Sun Apr 26, 2009 6:26 am UTC
Forum: School
Topic: Real that's what she said moment in school
Replies: 132
Views: 15143

### Re: Real that's what she said moment in school

French teacher telling a girl to get her homework out:

"Take it out fast, I'm coming!"
Wed Apr 08, 2009 6:49 am UTC
Topic: 0566: "Matrix Revisited"
Replies: 201
Views: 33812

### Re: "Matrix Revisited" Discussion

Okay, here's a challenge: think of a movie series in which the second one was better than the first. If that's too hard, and I think it might be, how about a series where the second was as good as the first? 8) Kim They had this discussion in Scream 2 (which is certainly not my answer D:). Nobody's...
Fri Sep 12, 2008 1:50 am UTC
Forum: Mathematics
Topic: find something about the number
Replies: 65
Views: 5349

### Re: find something about the number

49 is the least number not divisible by a number in the Fibonacci sequence.
Wed Aug 27, 2008 6:43 am UTC
Forum: Mathematics
Topic: Area under Curve
Replies: 37
Views: 3861

### Re: Area under Curve

Integration, differentiation, and even basic limits are not on the SAT or either of the math SAT IIs. Nevertheless, you'll need to learn them, and they're MATH!! The Math IIC SAT II usually has one simple limit problem on it, almost always one which involves factoring, canceling and plugging in (li...
Mon Aug 25, 2008 8:29 am UTC
Forum: Mathematics
Topic: Martingale betting system (Roulette)
Replies: 44
Views: 6122

### Re: Martingale betting system (Roulette)

I too thought of this a few months ago.

I wonder why people keep returning to this idea.
Thu Aug 14, 2008 8:33 am UTC
Forum: Science
Topic: Simple E&M question
Replies: 9
Views: 1494

### Re: Simple E&M question

Ah, thanks guys.

I'm sure I'll be posting again. Mechanics wasn't bad but E&M seems to be a little hard to grasp so far, although mechanics was too when I first started out.
Wed Aug 13, 2008 7:09 pm UTC
Forum: Science
Topic: Simple E&M question
Replies: 9
Views: 1494

### Re: Simple E&M question

So the consensus is that the angles are given and that they matter? (They seem to matter since I have to use them to add the vectors at the end).
Tue Aug 12, 2008 6:45 pm UTC
Forum: Science
Topic: Simple E&M question
Replies: 9
Views: 1494

### Simple E&M question

So I'm here reading my physics book. I got a little tired of mechanics so I jumped to E&M for a while and I find myself a little lost on one of the elementary problems. I'm sure this is some silly thing I've overlooked but here goes: The question is given 3 charges, q1 = +2Q, q2 = -2Q, q3 = -4Q,...
Tue Jul 29, 2008 2:28 am UTC
Forum: General
Replies: 169
Views: 22287

Sun Jul 27, 2008 8:10 am UTC
Forum: General
Replies: 169
Views: 22287

Sun Jul 27, 2008 1:54 am UTC
Forum: School
Topic: AP Physics Texts
Replies: 8
Views: 1577

### Re: AP Physics Texts

Thank you for your replies. I think I'm going to stick with the Halliday book. It's still quite detailed, it's about 1300 pages last time I checked. I'll be sure to post if I get stuck.
Sat Jul 26, 2008 6:37 pm UTC
Forum: School
Topic: AP Physics Texts
Replies: 8
Views: 1577

### AP Physics Texts

I'm going to make an attempt to self-study AP Physics C for the upcoming year. In school we use the Halliday book, Fundamentals of Physics. I paged through that and it looked alright, but does anybody with more experience learning physics have any pointers as to which book I should get? I'm looking ...
Fri Jul 25, 2008 12:12 am UTC
Forum: The Help Desk
Topic: Can't boot from hard drive
Replies: 4
Views: 1192

### Re: Can't boot from hard drive

Should reinstalling grub do the trick? I reinstalled it but no luck. ;_;
Thu Jul 24, 2008 1:10 am UTC
Forum: The Help Desk
Topic: Can't boot from hard drive
Replies: 4
Views: 1192

### Can't boot from hard drive

So I'm having a little problem here. I dug up this old computer and when I try to boot it gives me the whole "Primary hard disk drive 0 (and 1) not found". What's interesting is that when I boot my Gentoo live CD I can mount it and read it just fine. Udev maps it to hda1 so I think that me...
Wed Jul 23, 2008 2:32 pm UTC
Forum: School
Topic: AP Tests are here
Replies: 111
Views: 9917

### Re: AP Tests are here

Sophomore:

Biology - 5
Comp Sci AB - 5

I'm happy about Biology, I self-studied for that one and I thought I was close to the 4/5 cutoff. Just too many damn plant questions. >_>
Wed Jul 23, 2008 7:04 am UTC
Forum: General
Topic: REALLY Annoying Misconceptions
Replies: 4059
Views: 378683

### Re: REALLY Annoying Misconceptions

a thing wrote:I am not gay. I have high standards.

Yeah, she has to like you.

OOOH SNAP, YOU JUST GOT WRECKED etc.

Extra credit if anybody can tell me what show that's from.