已知|x+y+1|+(xy+3)²=0,求xy三次方+x三次方y

已知|x+y+1|+(xy+3)²=0,求xy三次方+x三次方y
已知|x+y+1|+(xy+3)²=0,求xy三次方+x三次方y

已知|x+y+1|+(xy+3)²=0,求xy三次方+x三次方y
由题可知,x+y+1=0 ,xy+3=0 即得 x+y=-1 ,xy=-3
（x+y)²=x²+2xy+y² ∴(-1)²=x²+2×（-3）+y² 即x²+y²=7
xy^3+x^3y=xy(x²+y²)=（-3）×7=-21