[latex] x^{4} + x^{3} - 8 x^{2} - 9x-9=0[/latex]

[latex]x^4+x^3-8x^2-9x-9=0 \\ x^4+x^3-9x^2+x^2-9x-9=0 \\ x^3(x+1)-9x(x+1)+x^2-9=0 \\ x(x+1)(x^2-9)+x^2-9=0 \\ (x^2-9)(x(x+1)+1)=0 \\ (x-3)(x+3)(x^2+x+1)=0 \\ \\ x-3=0 \ \ \ \textless \ =\ \textgreater \ \ x=3 \\ x+3=0 \ \ \ \textless \ =\ \textgreater \ \ x=-3 \\ \\ x^2+x+1=0 \\ D=1-4=-3\ \textless \ 0 \ - korney \ net \\ \\ OTBET: \ 3; \ -3[/latex]