(y+2)^2+4(y+2)=12
（y+2-2)(y+2+6)=0
得y=0 y=-8
y(y-2)=99
y^2-2y+1=100
(y-1))^2=100
得y=11 y=-9
1/2x^2=x+1
x^2-2x-2=0
x^2-2x+1=3
(x-1)^2=3
x=1+根号3 x=1-根号3
4x^2-6x-5=0
4（x^2-3/2x+9/16)=5+(9/4)
4(x-3/4)^2=29/4
x=3/4+根号29/4 x=3/4-根号29/4
(a^2-1)x^2-ax+a^2=0
x=1代入
(a^2-1)-a+a^2=0
（a-1)(2a+1)=0
a=1 a=-1/2
x^2+2x-1+m是一个完全平方式,求m的值
m=2
矩形的长和宽分别为x y,且x^2+y^2-2y-4x+5=0,求矩形的面积
x^2+y^2-2y-4x+5=0
(x-2)^2+(y-1)^2=0
x=2 y=1
矩形的面积=2*1=2