若x3+y3=1000,x2y-xy=-496,则(x3-y3)+(4xy2-2x2y)-2(xy2-y3)= ----

问题描述:

若x3+y3=1000,x2y-xy=-496,则(x3-y3)+(4xy2-2x2y)-2(xy2-y3)= ----