3（x-3）=(x-3)的平方
3(x-3)-(x-3)²=0
(x-3)(3-x+3)=0
(x-3)(6-x)=0
x1=3,x2=6
1.2y-0.04=(3y)的平方
(3y)²-1.2y+0.04=0
(3y-0.2)²=0
3y=0.2
y1=y2=1/15