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#101 Re: This is Cool » Why is this true » 2006-05-25 04:56:45
a can only be 9 because the x² must match on both sides since you have an equal sign, thus b can only be 2 due to the same reason with x, which reduces the number of variables to 2. On the left side of the equation you still have b²-9, which should be c according to the right side. With the already known b=2, c becomes -5. So the only variable you got left is x.
a, b and c can only equal 9, 2 and -5 respectively, anything else wouldn't solve the equation. This is if a, b and c is not a function of x, of course, and just numbers.
#102 Re: Dark Discussions at Cafe Infinity » We're surrounded by morons.. » 2006-05-10 08:47:04
Lots of studies has been made about connections with the two brain parts, if we can use them both in a more effective way than today, there's a whole lot of possibilities I think 
#103 Re: Dark Discussions at Cafe Infinity » We're surrounded by morons.. » 2006-05-10 04:53:57
I believe anyone can tell the first 50 from the top of their heads with enough practice, it's not that hard. But above 100, or even 10,000 I just don't understand. They can't be human 
#104 Re: Dark Discussions at Cafe Infinity » We're surrounded by morons.. » 2006-05-09 16:53:29
Well, as long as you know what a square number is, the problem should be easy. So he probably didn't know (or forgot!). But I remember square numbers being introduced quite early in school... 20%? And I thought it was horrible around here.
#105 Re: Help Me ! » Solving this DE (trigonometry) » 2006-05-05 00:45:07
It's solved now. Thanks George, even though it's not what I was looking for... again.
Anyway, the (easier) solution is y = 1/3cos(x)-cos(x)+C[cos(x)]^2. You get it by rewriting the integral I ended up with by using trigonometry rules and then use variable substitution to simplify the process.
Now I can go to sleep again :] thanks ganesh for that link, will have a look.
#106 Re: Introductions » hello =) » 2006-05-04 08:46:44
Seinfeld? It's latin for divinity, divine will; god, deity. Should've been numenloop, but I got lazy writing it, hah.
thanks.
#107 Re: Help Me ! » Solving this DE (trigonometry) » 2006-05-04 08:37:16
I've learned to not use formulas straight off like that, I learn nothing from it. Kinda ugly, yeah. But thanks anyway for showing that formula, might get in handy, though I preferably do everything from scratch.
Do you know, though, how to continue from where I left? Anyone else? I'll think about it some more, I simply can't sleep until I've figured it out =P
btw, is that LaTeX? How do I put it in here?
#108 Introductions » hello =) » 2006-05-03 22:42:26
- numen
- Replies: 6
I know I've been here before, I was registered too, but lost my login =P
Anyways, hello everyone! 
I'm 20, and studying math and physics at university, was hoping this place could be a bit of help, hehe. Currently reading linear algebra and integration methods. Fun, but hard ;]
Nice to meet you all.
#109 Help Me ! » Solving this DE (trigonometry) » 2006-05-03 22:33:54
- numen
- Replies: 8
the problem:
y' cos(x) + 2y sin(x) = ([sin(x)]^3)/(cos(x))
I know I could divide by cos(x) and calculate an integration factor, which I think would be 1/[cos(x)]^2 ?
Then I get: D(y/([cos(x)]^2)) = ([sin(x)]^3)/([cos(x)]^3)
Thus, the integral follows: ∫ ([sin(x)]^3)/([cos(x)]^4) dx, which I'm not sure how to solve...
Any ideas? I'm kinda stuck with this one, might be something wrong somewhere. My head just keeps spinning around 