单项式2x^2y,-2xy^2,-3x^2y,xy的和是多少
问题描述:
单项式2x^2y,-2xy^2,-3x^2y,xy的和是多少
答
2x^2y+(-2xy^2)+(-3x^2y)+xy
=2x^2y-2xy^2-3x^2y+xy
=-x^2y-2xy^2+xy