已知A=5mn－2m²＋3n²,B＝－3/2mn＋5m²＋n²/2,求﹣1/2 A＋B过程! 求解

已知A=5mn－2m²＋3n²,B＝－3/2mn＋5m²＋n²/2,求﹣1/2 A＋B过程! 求解
已知A=5mn－2m²＋3n²,B＝－3/2mn＋5m²＋n²/2,求﹣1/2 A＋B
过程! 求解

已知A=5mn－2m²＋3n²,B＝－3/2mn＋5m²＋n²/2,求﹣1/2 A＋B过程! 求解
解
-1/2A+B
=-1/2(5mn-2m²+3n²)+(-3/2mn+5m²+n²/2)
=(-5/2mn-3/2mn)+(m²+5m²)+(-3/2n²+1/2n²)
=-4mn+6m²-n²