先化简后求值:8m2-(6m2+15m2n)÷3m+m(n-1),其中m=2,n=-1.

问题描述:

先化简后求值:8m2-(6m2+15m2n)÷3m+m(n-1),其中m=2,n=-1.

8m2-(6m2+15m2n)÷3m+m(n-1),
=8m2-2m-5mn+mn-m,
=8m2-3m-4mn,
当m=2,n=-1时,原式=8×22-3×2+4×2,
=34.