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

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

人气：133 ℃　时间：2020-02-04 10:04:12

解答

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