x²-2x=0
(x-2)x=0
x-2=0或x=0
x1=2,x2=0
4x²=（x-1）²
4x²-(x-1)²=0
(2x+x-1)(2x-x+1)=0
(3x-1)(x+1)=0
x1=1/3, x2=-1