Question

I have no clue can someone help please?

Answer 1

Answer -7

Explanation:

0 = x^2 + 4x - 21

0 = x^2 - 3x + 7x - 21

0 = x(x-3) + 7(x-3)

0 = (x - 3)(x + 7)

Therefore x - 3 = 0 or x + 7 = 0

so x = 3 or x = -7