Question

$x^{4} + x^{3} - 8 x^{2} - 9x-9=0$

Answer 1

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