1.x^2-4x-12=0
(x-6)(x+2)=0
x=6或x=-2
2.y(y+5)=-25/4
y^2+5y+25/4=0
(y+5/2)^2=0
y=-5/2
3.3(x-3)=(x-3)^2
(x-3)^2-3(x-3)=0
(x-3)(x-3-3)=0
(x-3)(x-6)=0
x=3或x=6
4.(2x+3)^2=24x
(2x+3)^2-24x=0
4x^2+12x+9-24x=0
4x^2-12x+9=0
(2x-3)^2=0
x=3/2
5.1.2y-0.04=9y^2
9y^2-1.2y+0.04=0
(3y-0.2)^2=0
(3y-1/5)^2=0
y=1/15