若4x^2+8xy+4y^2+4y-3=0,求x+y的值
问题描述：
若4x^2+8xy+4y^2+4y-3=0,求x+y的值
答
4x^2+8xy+4y^2+4x+4y-3
=4(x+y)^2+4(x+y)-3
=[2(x+y)-1][2(x+y)+3]
=0
2(x+y)-1=0或2(x+y)+3=0
x+y=1/2或x+y=-3/2