已知A=8x2y-6xy2-3xy,B=7xy2-2xy+5x2y,若A+B-3C=0,求C-A.
问题描述:
已知A=8x2y-6xy2-3xy,B=7xy2-2xy+5x2y,若A+B-3C=0,求C-A.
答
由题意得:3C=A+B=8x2y-6xy2-3xy+7xy2-2xy+5x2y=13x2y+xy2-5xy,
∴C=
,13x2y+xy2−5xy 3
故:C-A=
-(8x2y-6xy2-3xy),13x2y+xy2−5xy 3
=
-8x2y+6xy2+3xy,13x2y+xy2−5xy 3
=-
x2y+11 3
xy2+19 3
xy.4 3