Can anyone explain how this follows? Has it been factories and simplified?
Yes thanks, it's all quite straight forward from there. I think I need to revisit algebraic long division though it's been about 3 years since I've used it!
RE the method used directly above, in general when given:
A/B = (C.B)/B - D/B = C - D/B ???
This bears some resemblance to completely the square?