解析
x^2-8x=0
x(x-8)=0
x=0或x=8
(2)(3y-4)^2=y^2
9y^2-24y+16=y^2
8y^2-24y+16=0
y^2-3y+2=0
(y-1)(y-2)=0
y=1或y=2