已知x^2+2xy+y^2-10y+26=0,求(1)x+2y的平方根 (2)2y+2x的立方根

∵x²+2x+y²-10y+26=0
x²+2x+1+y²-10y+25=0
(x+1)²+(y-5)²=0
∴x+1=0 y-5=0
x=-1 y=5
∴①√(x+2y)=√(-1+10)=√9=3
②³√(2y+2x)=³√(10-2)=2