42cos(x)  28sin(7x + pi/2)
28?
D'oh. No, 42  28 ... uhhh. *gets out calculator* 14?
From: evan 20070719 09:24 pm (UTC)
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I answered it below.
I got a real easy one...
p(x) = x^2 + 2x + 1 find the real roots of the polynomial
hillarious though!
I got 3 * (4)  (2) = ?
See, I didn't need to take Calculus after all!
that should be the test to prove you're Asian.
That's better than a password ;)
7*6*cos(12pi)  4*7*sin(14pi + pi/2) = 4228 = 14
 From: mart 20070719 06:50 pm (UTC)
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Quick! Write an OCR system that can grok mathematical notation!
 From: erik 20070719 07:08 pm (UTC)
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The answer is 7 you guys. I just did it in my head.
From: evan 20070719 07:20 pm (UTC)
possibly embarrassing myself here  (Link)

I forget calculus syntax. Is that asking you to just evaluate at x=2pi? In that case, the sin is +1 and the cos is 1 at that point, so it's just 7  4 = 3.
 From: erik 20070719 07:54 pm (UTC)
Re: possibly embarrassing myself here  (Link)

You mean I was only off by 4?! Not bad!
 From: zarex 20070719 08:22 pm (UTC)
Re: possibly embarrassing myself here  (Link)

You have to take the derivative first, then evaluate it at the point x=2pi. Anyway, sin(N*2pi)=0, cos(N*2pi+pi/2)=0.
From: evan 20070719 09:22 pm (UTC)
Re: possibly embarrassing myself here  (Link)

I meant "evaluate the derivative", and "the sin is +1" I meant "the derivative at that point is +1". Nikolas did it more thoroughly below.
 From: zarex 20070719 09:45 pm (UTC)
Re: possibly embarrassing myself here  (Link)

He messed up too. :) Must be a lot of programmers hanging around here, and not enough engineers.
 From: nibot 20070719 10:18 pm (UTC)
Re: possibly embarrassing myself here  (Link)

I think you both forgot to apply the chain rule. The derivative of 7Sin[6x] is 42 Cos[6x], etc. (Deleted comment)
From: evan 20070719 09:23 pm (UTC)
Re: Spelling it out ...  (Link)

Alternatively, what I did was visualize what the derivatives at those wellknown points are: the sin is maximally sloping upwards (+1) and the cos maximally downwards (1), which got me to your secondtolast step without computing any derivatives directly. :)
 From: zarex 20070719 09:44 pm (UTC)
Re: Spelling it out ...  (Link)

You missed a factor on the derivative. D[ sin(ax) ] = a*cos(ax) . Remember D[ sin(u) ] = cos(u)du . See my solution above.
 From: nibot 20070719 10:15 pm (UTC)
you forgot the chain rule  (Link)

zarex has the correct answer above, 14.
From: evan 20070719 10:23 pm (UTC)
Re: Spelling it out ...  (Link)

Haha, we suck. Chain rule?
There was a time when I could actually do the math. Now it's like a bad dream. uffff.
I took 2 years of AP Calc in high school, and now, I hardly remember a lick of it!
Cincinnati State Tech. a looong time ago :)
Yeah, yeah, it's funny and all, but wouldn't this be pretty simple for a computer, and pretty damn hard for most humans.
From: evan 20070719 09:23 pm (UTC)
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I think it may have been intentionally constructed to be easy. See my comments above.
Except for the fact that you have to OCR and parse a math equation correctly.
so if you know the answer does that mean you're a computer or human? i think humans would get the wrong answer. i know i would.
Either I'm not a human or I'm totally blonde... _"
i always knew i wasnt a real person...
cause computers are terrible at math
So, if you get the correct answer, you must be automated.
 From: ossie 20070720 09:17 am (UTC)
after a few reloads  (Link)

I got the question
6+71=?
so I am human
 From: alenja 20070720 10:21 am (UTC)
great  (Link)

so..now I have a lot of variants who I am martian, animal, machine... but i'm quite sure that i'm not human!
wtf? 