已知（x+y-1）2与根号2x-y+4互为相反数,求x2+y3的平方根.

已知（x+y-1）2与根号2x-y+4互为相反数,求x2+y3的平方根.

（x+y-1）²与根号2x-y+4互为相反数
则(x+y-1)²+√(2x-y+4)=0
则x+y-1=0
2x-y+4=0
两式相加,得3x+3=0,解得x=-1
代入x+y-1=0,得y=2
所以x²+y³=1+8=9

（x+y-1）2与根号2x-y+4互为相反数
x+y-1=0
2x-y+4=0
x=-1
y=2
x2+y3
=1+8
=9