已知m^2+2mm=484,3mm+2n^2=560,求代数式2m……2=13mn+6n^2-440_数学解答

已知m^2+2mm=484,3mm+2n^2=560,求代数式2m……2=13mn+6n^2-440

人气：499 ℃　时间：2020-04-14 15:21:55

解答

2m^2+13mn+6n^2-440
=(2m^2+4mn)+(9mn+6n^2)-440
=2(m^2+2mn)+3(mn+2n^2)-440
=2x484+3x560-440
=2208