Question

When factored, the trinomials x^2-2x-15 and x^2-9x+20 have one binomial factor in common. What is this factor?

1. x-7
2. x+7
3. x-5
4. x+5

Answer 1

x^2-2x-15
(x-5)(x+3)

Proof:
-5+3=-2
-5*3=-15

x^2-9x+20
(x-4)(x-5)

Proof:
-4-5=-9
-4*-5=20

Final answer: (x-5)