x^3+y^3=(x+y)(x^2-xy+y^2)
x^-xy+y^2=10
(x+y)^2=100
x^2+2xy+y^2=100
3x^2+3y^2=120
x^2+y^2=40
(100+99)(100-99)+(98+97)(98-97)+.+(2+1)(2-1)
=100+99+98+97+.+2+1
=(1+100)100/2
=5050