Question

How do you simplify `\frac { 5x ^ { 3} + 9x ^ { 2} - x - 6} { ( x + 1) ( x - 1) ( 1- x ^ { 2} ) }`?

Answer 1

`(1-x^2)=(1-x)(1+x)`

If we put this into our fraction we get

`[5x^3+9x^2-x-6]/[(x+1)(x-1)(1-x)(1+x)]`

But `5x^3+9x^2-x-6` does not factorise ( I don't think!) so we can't cancel down.