x⁴(x-1)-2x²(x-1)+x-1=0
(x-1)(x⁴-2x²+1)=0
(x-1)(x²-1)²=0
(x-1)(x²-1)(x²-1)=0
(x-1)(x-1)(x+1)(x-1)(x+1)=0
(x-1)³(x+1)²=0
x1=1, x2= -1
x^4(x-1)-2x^2(x-1)+x-1=0
(x-1)(x^4-2x^2+1)=0
(x-1)(x^2-1)(x^2-1)=0
