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

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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
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

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
∵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

m-3n=-1.然后直接带入值即可

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

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

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