The answer is:4x³ +8x² +4x

So clearly I have done this incorrectly as I put the answer as '4x^4 +8x³ +4x²'

You can probably guess what I've done wrong, as I thought I had to remove the fraction by multiplying all the terms by the denominator.

It seems as though everything is multiplied as though the fraction isn't there. What am I supposed to do?