Factor the trinomial.

Question

x^2-x-20

Select the correct choice below.

(a) x^2-x-20=?

(b) The polynomial is prime.

Answer 1

Because a quadratic trinomial can have two solutions, x₁ and x_2, it can ve factored in the following way

                         x^2 -x -20 = (x -x₁)(x-x₂)   (when the first coefficient in the trinomial is equal 1)

 x1 and x2 are factors of -20 such that x1 +x2 = -(-1) =1. It is easy to see that  x1 = 5, x2 = -4.

                 Thus, we have    x^2 - x - 20 = (x-5)(x+4)