先化简,再求值.6.如果m-3n+1=0,求4﹙m-3n﹚²-m+3n-5﹙m-3n﹚²-7的值
问题描述：
先化简,再求值.6.如果m-3n+1=0,求4﹙m-3n﹚²-m+3n-5﹙m-3n﹚²-7的值
答
4﹙m-3n﹚²-m+3n-5﹙m-3n﹚²-7
=-﹙m-3n﹚²-m+3n-7------合并同类项
=-﹙m-3n﹚²-﹙m-3n﹚-7
=-（-1）²-（-1）-7
=-7
注：m-3n+1=0
则m-3n=-1
答
m-3n+1=0，得m-3n= -1。4﹙m-3n﹚²-m+3n-5﹙m-3n﹚²-7=4﹙m-3n﹚²-（m-3n）-5﹙m-3n﹚²-7=4*（-1）²-（-1）-5（-1）²-7=4+1-5-7= -7
答
m-3n+1=0
m-3n=-1
4﹙m-3n﹚²-m+3n-5﹙m-3n﹚²-7
=-(m-3n)-﹙m-3n﹚²-7
=-(-1)-(-1)²-7
=-7
答
m-3n=-1.然后直接带入值即可
答
∵m-3n+1=0
∴m-3n=-1
4﹙m-3n﹚²-m+3n-5﹙m-3n﹚²-7
＝4﹙m-3n﹚²-(m-3n)-5﹙m-3n﹚²-7
=-(m-3n)²-(m-3n)-7
=-(-1)²-(-1)-7
=-1+1-7
=-7