Question

х^3-х^2-4х^2+4х-21х+21=0

Answer 1

$x^3-x^2-4x^2+4x-21x+21=0 \x^2(x-1)-4x(x-1)-21(x-1)=0 \(x-1)(x^2-4x-21)=0 \x-1=0 \x_1=1 \x^2-4x-21=0 \D=16+84=100=10^2 \x_2= frac{4+10}{2} =7 \x_3= frac{4-10}{2} =-3$
Ответ: x1=1; x2=7; x3=-3