Question

(x^2-2x)^2-7(x^2-2x)-8=0

Answer 1

$a-b+c=0\Rightarrow x=\left \{ -1;-\frac{c}{a} \right \}\\x^2-2x=\left \{ -1;8 \right \}\\\left[ \begin{gathered} x^2-2x+1=0; \\ x^2-2x-8=0 \\ \end{gathered} \right.\Rightarrow x=\left \{ -2;1;4 \right \}$