x3+y3=100
(x+y)(x^2-xy+y^2)=100
因x+y=1
所以
x^2-xy+y^2=100
(x+y)^2-3xy=100
1-3xy=100
xy=-33
x^2+y^2
=(x+y)^2-2xy
=1-2*(-33)
=67