若2m²+3mn=13,3mn+2n²=21,则4m²+15mn+6n²-44=?

分类: 作业答案 • 2021-12-31 20:50:49

问题描述：

答

4m^2+15mn+6n^2-44
=4m^2+6mn+9mn+6n^2-44
=2(2m^2+3mn)+3(3mn+2n^2)-44
=2*13+3*21-44
=26+63-44
=89-44
=45