Question

x^2+8x-20
I got my answer for 4,5
but would it be (x-4)(x-5)
(x+4)(x+5), ??

Answer 1

no, notice how 4 and 5 add to 9 (not 8) and how -4 and -5 add to -9 (still not 8)

Answer 2

your roots would be have to add up to 8, so the factor would be (x+10)(x-2)