(x^2-2x)^2-7x^2+14x-8=0
(x^2-2x)^2-7(x^2-2х)-8=0
х^2-2x=у
у^2-7y-8=0
y1=8 y2=-1
x^2-2x=8 x^2-2x=-1
x^2-2x-8=0 x^2-2x+1=0
x1=-2 x2=4 x3=1 x4=1