4m²-5m【-m＋2n-1】＋4m【-2m-3n＋2】
=4m²＋5m²-10mn＋5m-8m²-12mn＋8m
=m²-22mn＋13m
因为m=2,n=1
所以
原式=2²-22×2×1＋13×2
=4-44＋26
=-14