Question

Factorise and solve x^2 + 4x -21 = 0

Answer 1

(x+7)(x-4) x=-7,4

Explanation:

The factors of -21 that add up to 4 are 7 and -3, so put those as your two second values in your binomials and solve for x, in this case being the negative versions of the second term in the binomial

Answer 2

(x + 7) (x - 3)

Explanation:

Find 2 numbers that add to 4 and multiply to -21

(x + 7) (x - 3)