4m²-5m【-m+2n-1】+4m【-2m-3n+2】其中m=2,n=-1化简求值
问题描述:
4m²-5m【-m+2n-1】+4m【-2m-3n+2】其中m=2,n=-1
化简求值
答
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