先化简,再求值,-2(mn-3m²)-[m²-5(mn-m²)+2mn],其中m=-1,n=-2
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/28 04:07:56
![先化简,再求值,-2(mn-3m²)-[m²-5(mn-m²)+2mn],其中m=-1,n=-2](/uploads/image/z/594320-32-0.jpg?t=%E5%85%88%E5%8C%96%E7%AE%80%2C%E5%86%8D%E6%B1%82%E5%80%BC%2C-2%EF%BC%88mn-3m%26%23178%3B%EF%BC%89-%5Bm%26%23178%3B-5%EF%BC%88mn-m%26%23178%3B%EF%BC%89%2B2mn%5D%2C%E5%85%B6%E4%B8%ADm%3D-1%2Cn%3D-2)
先化简,再求值,-2(mn-3m²)-[m²-5(mn-m²)+2mn],其中m=-1,n=-2
先化简,再求值,-2(mn-3m²)-[m²-5(mn-m²)+2mn],其中m=-1,n=-2
先化简,再求值,-2(mn-3m²)-[m²-5(mn-m²)+2mn],其中m=-1,n=-2
-2(mn-3m²)-[m²-5(mn-m²)+2mn]
=-2mn+6m²-m²+5(mn-m²)-2mn
=-2mn+6m²-m²+5mn-5m²-2mn
=mn
当m=-1, n=-2时,
原式=(-1)×(-2)
=2