已知|x-y+3|与2（x+y）²互为相反数,求x²+2xy+y²的值．

已知|x-y+3|与2（x+y）²互为相反数,求x²+2xy+y²的值．
已知|x-y+3|与2（x+y）²互为相反数,求x²+2xy+y²的值．

已知|x-y+3|与2（x+y）²互为相反数,求x²+2xy+y²的值．
|x-y+3|与2（x+y）²互为相反数
x-y+3=0
x+y=0
x=-3/2
y=3/2
x²+2xy+y²
=(x+y)²
=0

必有x-y+3=0以及x+y=0
故x=3/2，y--3/2
x²+2xy+y²=（x+y）^2=0

|x-y+3|与2（x+y）²互为相反数，|x-y+3|+2（x+y）²=0
|x-y+3|与2（x+y）²都为非负数，则|x-y+3|=0，2（x+y）²=0
x-y+3=0,x+y=0可求x，y