Answer:
x1= -2
x2= 1
x3= 4
Step-by-step explanation:
[tex]\\ \sf\longmapsto (x^2-2x)^2-8=7(x^2-2x)[/tex]
[tex]\\ \sf\longmapsto x^4-4x^3+2x^2-8=7x^2-14x[/tex]
[tex]\\ \sf\longmapsto x^4-4x^3-5x^2+14x-8=0[/tex]
No real roots (pic attached)
