Question

Which are factors of x2 – 4x – 5? Check all that apply. (x – 5) (x – 4) (x – 2) (x + 1) (x + 5)

Answer 1

x^2 – 4x – 5 = (x - 5)(x + 1)
cause
(x - 5)(x + 1) = x^2 -5x +x - 5= x^2 -4x - 5

so (x - 5) and (x + 1) are factors

answer
(x - 5) and (x + 1) 

Answer 2

X² - 4x - 5
x          -5
x           1

(x-5)(x+1) is your answer

none of the others work, because they wont give you the desired number in the middle, -4x

hope this helps