# Not clear on what happened (subtraction of two fractions with variables to exponents)

1. Sep 4, 2012

### Tubefox

-2((1/((x^2 + 1)^2 )) - ((4x^2 )/(x^2 +1)^3 )) = 6x^2-2/(x^2+1)

This is actually the last step of this problem. I understand everything they did up until here, but I'm a bit confused as to how they got from their last step, to the actual answer. Could someone explain?

2. Sep 4, 2012

### CAF123

Re: Not clear on what happened (subtraction of two fractions with variables to expone

Are you missing a '-' in front of the coefficient of the $x^2$ term and should that be $(x^2+1)^3 ?$

3. Sep 4, 2012

### Ray Vickson

Re: Not clear on what happened (subtraction of two fractions with variables to expone

Don't you mean (6x^2 - 2)/(x^2 + 1)? You wrote 6x^2 - 2/(x^2+1), which is a completely different thing.

RGV