若x的三次方+y的三次方=27,x²-xy+y²=9,则x+y=...

问题描述:

若x的三次方+y的三次方=27,x²-xy+y²=9,则x+y=...

x^3+y^3
=(x+y)(x^2-xy+y^2)
x+y=27÷9=3