# Thread: How do you get from one stage to the other.

1. ## How do you get from one stage to the other.

I've always been useless with logs, help please! How did they get from line one to line two?

2. Originally Posted by bluebiro
I've always been useless with logs, help please! How did they get from line one to line two?

Only the two fractions in the bracket are collected:

$\displaystyle -\dfrac14\left(\dfrac1{x+1}+\dfrac1{x-1}\right) = -\dfrac14\left(\dfrac{x-1 + x+1}{(x+1)(x-1)}\right) = -\dfrac14\left(\dfrac{2x}{x^2-1}\right) = -\dfrac12\left(\dfrac{x}{x^2-1}\right)$