4В.38 4В.39 и 4В.40
пожалуйста

$x^3+x^2-9x-9=0 x^2(x+1)-9(x+1)=0 (x+1)(x^2-9)=0 (x+1)(x-3)(x+3)=0 x_1=-1; x_2=3; x_3=-3$

$2x^3+8x=x^2+4 2x(x^2+4)-(x^2+4)=0 (x^2+4)(2x-1)=0 [ x^2+4 textgreater 0] 2x-1=0 x= frac{1}{2}$

$3x^3-x^2+18x-6=0 3x^2(x- frac{1}{3}) +18(x- frac{1}{3}) =0 (x- frac{1}{3}) (3x^2+18) =0 [3x^2+18 textgreater 0] x- frac{1}{3}=0Rightarrow x= frac{1}{3}$

$x^3-5x^2+9x-5=0 x^3-x^2-4x^2+4x+5x-5=0 x^2(x-1)-4x(x-1)+5(x-1)=0 (x-1)(x^2-4x+5)=0 (x-1)((x-2)^2+1)=0 [(x-2)^2+1 textgreater 0] x-1=0 Rightarrow x=1$

$x^3-27x=0 x(x^2-27)=0 x(x-3 sqrt{3} )(x+3 sqrt{3} )=0 x_1=0 ; x_2=3 sqrt{3} ; x_3=-3 sqrt{3}$

$x^3-18x=0 x(x^2-18)=0 x(x-3 sqrt{2} )(x+3 sqrt{2} )=0 x_1=0 ; x_2=3 sqrt{2} ; x_3=-3 sqrt{2}$