Question

решите уравнение x^3+3x^2-18x-54=0

Answer 1

$x {}^{3} + 3x {}^{2} - 18x - 54 = 0 \\ x {}^{2} (x + 3) - 18(x + 3) = 0 \\ (x + 3)(x {}^{2} - 18) = 0 \\ ( x + 3)(x - \sqrt{18} )(x + \sqrt{18} ) = 0 \\ x1 = - 3 \\ x2 = \sqrt{18}$

$x3 = - \sqrt{18}$