Question

Cameron factored x2 + 13x - 140 as (x – 7)(x + 20)

Amanda factored x2 + 13x - 140 as (x – 20)(x + 7).

Who factored the trinomial correctly?

Answer 1

Cameron factored correctly

Explanation:

x² + 13x - 140

consider the factors of the constant term (- 140) which sum to give the coefficient of the x- term (+ 13)

the factors are + 20 and - 7 , since

20 × - 7 = - 140 and + 20 - 7 = + 13 , then

x² + 13x - 140 = (x - 7)(x + 20)

note that Amanda has - 20 and + 7

then - 20 + 7 = - 13 when + 13 is required for the x- term