So I have to do a review in my Precalculus textbook from Algebra 2 and their are these 3 questions that I just don't seem to understand. I have the answer in the back of the book but I want to know how to get to the answer.

Questions are:

1-8x^2-9x^4 - Answer is -(3x-1)(3x+1)(x^2-1)

(x+2)^2 - 5(x+2) - Answer is - (x+2)(x-3)

3(x^2+10x+25) - 4(x+5) - Answer is (x+5)(3x+11)

I Just don't undestand how they got to those answers.