if.... 2s² + 5s -3 = (2s -1)(s +3)

what does 9s² - 24s +16 = ? and how is this achieved

I know how to multiply the brackets out to get the single expression but i forget how to get a two bracket statement for a single expression can anyone show me the method please.....

This is a single step in a four page laplace transformation with partial fractions, I understand the hard part its this single bit of algebra i forget.....

is it just a case of trial and error with different values ?

Taff