Question

x в кубе + 3х в квадрате - 4х -12 = 0

Answer 1

$x {}^{2} \times (x + 3) - 4(x + 3) = 0 \\ (x + 3) \times (x {}^{2} - 4) = 0 \\ x + 3 = 0 \\ x {}^{2} - 4 = 0 \\ x = - 3 \\ x = - 2 \\ x = 2$