已知,4m+n=90,2m-3n=10,求(m+2n)²-(3m-n)²的值

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已知,4m+n=90,2m-3n=10,求(m+2n)²-(3m-n)²的值已知,4m+n=90,2m-3n=10,求(m+2n)²-(3m-n)²的值已知,4

已知,4m+n=90,2m-3n=10,求(m+2n)²-(3m-n)²的值
已知,4m+n=90,2m-3n=10,求(m+2n)²-(3m-n)²的值

已知,4m+n=90,2m-3n=10,求(m+2n)²-(3m-n)²的值
4m+n-2m+3n=2m+4n=80
m+2n=40
4m+n+2m-3n=6m-2n=100
3m-n=50
(m+2n)²-(3m-n)²=40²-50²=-900