(2014•常熟市一模)若m-n=2,则2m2-4mn+2n2-1的值为______.
1个回答
原式=2(m
2
-2mn+n
2
)-1,
=2(m-n)
2
-1
∵m-n=2,
∴原式=2×4-1
=7.
故答案为:7.
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