Question

数学老师在黑板上布置的作业中有这样的一道题：先化简，再求值

Answer 1

(-x^3+3x^2y-y^3)-(x^3-2xy^2+y^3)+(2x^3-3x^2y-2xy^2)
=-x^3+3x^2y-y^3-x^3+2xy^2-y^3+2x^3-3x^2y-xy^2
=-2y^3不含x项,所以结果正确