Respuesta :
answer is x = -7 and x = -3
x2 + 10x = -21
x2 + 10x + 21 = 0
(x +3) (x +7) = 0
(x +3) = 0
and
(x + 7) = 0
so x = - 3 and x = -7
x2 + 10x = -21
x2 + 10x + 21 = 0
(x +3) (x +7) = 0
(x +3) = 0
and
(x + 7) = 0
so x = - 3 and x = -7