已知:4x^2+4xy+2y^2+6y+9=0 ,求x-y的值

问题描述:

已知:4x^2+4xy+2y^2+6y+9=0 ,求x-y的值

4x^2+4xy+2y^2+6y+9=0
(2x+y)^2+(y+3)^2=0
2x+y=0
y+3=0
x=3/2
y=-3
x-y=3/2+3=9/2