(1)3y²+6y-4=0
y²+2y=4/3
y²+2y+1=7/3
(y+1)²=7/3
y=-1+√21/3 y=-1-√21/3
(2)x²+4x-9=2x-11
x²+2x+1=-1
(x+1)²=-1
无解
(3)x(x+4)=8x+12
x²-4x-12=0
(x-6)(x+2)=0
x=6 x=-2