Question

Решите урвнение:     $x^{3}+2x^{2}-9x-18=0$

Answer 1

$x^3+2x^2-9x-18=0;\\(x^3+2x^2)-(9x+18)=0;\\x^2(x+2)-9(x+2)=0;\\(x^2-9)(x+2)=0;\\(x^2-3^2)(x+2)=0;\\(x-3)(x+3)(x+2)=0;\\x-3=0;x_1=3;\\x+3=0;x_2=-3;\\x+2=0;x_3=-2$