GIVEN:

remember:

And

SOLVE:
start by multiplying the factors:

simplify by combing like terms. Most terms subtract off, leaving:

This can be factored, but it is not a perfect square, which is really what we need to take the square root.

I'm not exactly sure what form they want the answer in...
so taking the square root:

so my best answer is:

or the more factored form:

I'm not sure how else to solve it. Taking the square root doesn't work out super well, so I left it in the most simple form I could.
sorry for not coming to a definitive answer!