Ah, i now see what i did wrong, haha. ty Colster
the problem is you have to take the integral from the f(x) intersection to 1.
A(square) = 1*1 = 1
A(square)/2 = 0.5
x interception = z
integral{x0to[1]}(f(x)) = 0.5
[x*ln(x)-x+a*x] {x0to[1]} = 0,5
1*ln(1)-1+a*1 - [x0*ln(x0)-x0+a*x0] = 0.5 --> equation 1
ln(x0) + a = 0
ln(x0) = -a
x0 = e^(-a)
x0 -> equation 1
-1 + a - (e^(-a))*ln(e^(-a)) + e^(-a) - a*e^(-a) = 0,5 |+1
a + a*e^(-a)) + e^(-a) - a*e^(-a) = 1,5
a + ( e^-a) = 1,5
solution 1: 1.198290437
solution 2: -.8576766739
2 doesnt make any sense, so its
test:
f(x) = ln(x) + 1.198290437
x0 = e^(-1.198290437) = .3017095628
integral from .3017095628 to 1 f(x) = 0.5
problem solved, its 1.198290437
edit: so camicio is right, just wanted to solve the problem, i like mathematics (flames inc)
Last edited by Colster; 03-12-2009 at 07:51 AM.
Ah, i now see what i did wrong, haha. ty Colster
The answer is definitely over 9000 (never mind, it was answered already hehe).
I'm a high school sophomore, and I'm very interested in how this problem is solved. However, I don't think I've ever been taught how to solve this (I'm in the equivalent of AP Algebra II this year and am going into AP Pre-calculus next year). Is this a calculus problem?
What was wrong with my answer: a = -ln(x)+x ?
Ah I didn't see this...I could have done it lol.
The maths isn't that hard, it just requires a bit of thinking to work out what equations to solve
Actually, no, that bit isn't wrong. f(x) = ln(x) + a.
integral ( f(x) )
= integral ( ln(x) + a )
= integral ( ln(x) ) + ax + c
Using integral uv' = uv - integral vu',
integral ln(x)
= xln(x) - integral 1
= xln(x) - x
Hence,
integral ( ln(x) ) + ax + c
= xln(x) - x + ax + c
= xln(x) + (a-1)x + c
And it's what I said! Whay!
(yes, I know it's been solved)
Lol, you're right blubb12345. Do more giveaways like this please, I'll solve the next one hopefully.
guitargod218 you just need to know how to integrate logarithms, know what an integral is and avoid doing stupid errors or making stupid assumptions.
tamen, a is supposed to be a real constant number.
Think this one was the hardes math problem ive ever solved tbh, haha and i got a account out of itsweet and ty
uh sry missed the
=xlnx + ax + c - integral of 1
saw that the -x missed
your mistake is that you chose the wrong upper limit for the integral
the upper limit is where f(x)=1 but you chose 1 but thats wrong so it becomes wrong where you equalize
F(x0)-F(1)=0.5
it should be
F(x0)-F(x1)+1-x1=0,5
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X= over 9000!!!! Gief account nao den!! Pliiiiiiiz
Ah, of course, that would be it. Thanks, blubb. It annoys me if I get something wrong and can't figure out where it went balls up. Not that I ever really intend on going back over it, I just like to know XD