(8xy-3x2)-5xy-3(xy-2x2+3)

问题描述:

(8xy-3x2)-5xy-3(xy-2x2+3)
已知A=x3+x2-x+1,B=-x3-x2+x+1,当x=-2时,求A-2B的值.

A=-6-4+2+1=-7,B=6+4-2+1=9
A-2B=-7-2x9=-25