已知A=3m^2-2N^2+mn,B=5MN-6M^2且满足A-B+3C=0

问题描述:

已知A=3m^2-2N^2+mn,B=5MN-6M^2
且满足A-B+3C=0

由条件可知:3C=B-A
化简B-A=3C=2N^2+4MN-9M^2