(х-2)*(х+8х+16)=7*(х+4)

(х - 2) * (х^2 + 8x + 16) = 7(x + 4);

(х - 2) * (x + 4)^2 = 7(x + 4);

(х - 2) * (x + 4)^2 - 7(x + 4) = 0;

(х + 4) * ((x 2) * (x + 4) - 7) = 0;

(х + 4) * (x^2 + 4x 2x - 8 - 7) = 0;

(х + 4) * (x^2 + 2x - 15) = 0;

х + 4 = 0    или     x^2 + 2x - 15 = 0;

х₁ = -4;                D = b^2 - 4 * ac = 2^2 4 * (-15) = 4 + 60 = 64;

                            x_2,3 = (-b sqrt (D)) / 2a;

                            x₂ = (-2 + sqrt (64)) / 2 = (-2 + 8) / 2 = 3;

                            x₃ = (-2 - sqrt (64)) / 2 = (-2 - 8) / 2 = -5.

Ответ: х₁ = -4; х₂ = 3; х₃ = -5.