3y^2=12y
3y^2-12y=0
3y(y-4)=0
y1=0 ,y2=4
3x^2-5x=0
x(3x-5)=0
x1=0,x2=5/3
（x+3)^2=2x(x+3)
x^2+6x+9=2x^2 + 6x
x^2=9
x1=3, x2=-3