2.已知A=x^3-2xy^2+1,B=x^3+xy^2-3x^2y,求3A-B.

问题描述:

2.已知A=x^3-2xy^2+1,B=x^3+xy^2-3x^2y,求3A-B.

A = x^3 - 2 x y^2 + 1
B = x^3 + x y^2 - 3 x^2 y
3 A - B
=3 + 2 x^3 + 3 x^2 y - 7 x y^2