Help me solve this!

[Princess9000]

(a^2-b^2)/(a^3+b^3)* [1/a^2-1/ab+1/b^2]* (a^3b^3)/(a-b)^2-a^2/(a-b)
The answer is -a!
But i got stuck!

 

[Princess9000]

u = (a^2 - b^2) / (a^3 + b^3)
v = 1 / a^2 - 1 / ab + 1 / b^2
w = (a^3 b^3) / (a - b)^2
x = a^2 / (a - b)

So you have u * v * w - x

-a is correct as answer.
YOU were asked to solve, not us!
If you want help, SHOW what you've done; you got stuck where?

I know but i dont know where to start!
Please help me¡

 

[JeffM]

I know but i dont know where to start!
Please help me¡

I am afraid that problems like this just require you to grab one end of the thread and start unraveling the mess.

I presume that the problem says to simplify that horror show. So what I do is to start with the ugliest part first; that way it will be down hill from there. What denis called v looks ugliest to me so let's start there.

\(\displaystyle v = \dfrac{1}{a^2} - \dfrac{1}{ab} + \dfrac{1}{b^2}.\) Pretty sickening at first glance. But what do we do to add fractions? We check whether they have a common denominator. Do these have a common denominator? No. So then what do we do? We create one. How might you do that here?

Edit: By the way, what denis did was a good idea on many problems that look complex. He broke it down into simpler pieces. Good trick to learn.