已知:4x^2+4xy+2y^2+6y+9=0 ,求x-y的值

已知:4x^2+4xy+2y^2+6y+9=0 ,求x-y的值
已知:4x^2+4xy+2y^2+6y+9=0 ,求x-y的值

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

4x²+4xy+2y²+6y+9=0
4x²+4xy+y²+y²+6y+9=0
(4x²+4xy+y²)+(y²+6y+9)=0
(2x+y)²+(y+3)²=0 两个非负数的和等于0，只有这两个数等于0
2x+y=0
y+3=o
x=3/2
y=-3
x-y=9/2

x=1.5
y=-3