First factor out the x from the numerator, and factor the denominator:
Now the trick is this: Is divisible by either (x-1) or (x+1). It turns out (and it usually does!) that it is, in this case, divisible by (x-1). You will have to do synthetic or polynomial division (which I don't know how to do on this website!) as follows:
1 | 1 -4 0 3
XXX 1 -3 -3
XX 1 -3 -3 0
Other tutors could probably write it better, but basically, the remainder is zero, and the quotient is
Therefore the x-1 divides out leaving this:
By the way, the remaining trinomial does not factor.