Помогите!!! (х² - 6х)² + 2(х - 3)² = 81

Question

Помогите!!! (х² - 6х)² + 2(х - 3)² = 81

Answer 1

(x²-6x)²+2x²-12x+18-81=0,
(x²-6x)²+2(x²-6x)-63=0,

x²-6x=t,  t²+2t-63=0,

t=-9        t=7
 x²-6x=-9         x²-6x=7
 x²-6x+9=0         x²-6x-7=0

x=3                    x=7    x=-1