若实数a满足a²-2a+1=0，求2a²-4a+5的值是多少？？

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由题意可知a=1,所以2×1方-4×1＋5=7。

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解
a²-2a=-1
∴2a²-4a=-2
∴2a²-4a+5
=(-2)+5
=3

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∵a²-2a+1=0
∴a=1
∴2a²-4a+5
=2×1²-4×1+5
=3

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a=1 代入得3

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