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已知函数f(x)=(x-2)2,f′(x)是函数f(x)的导函数,设a1=3,an+1=a...
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已知函数f(x)=(x-2)
2,f′(x)是函数f(x)的导函数,设a
1=3,a
n+1=a
n-
![](data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAxCAYAAAC78KvKAAAAAXNSR0IArs4c6QAAAARnQU1BAACx
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)
(I)证明:数列{a
n-2}是等比数列,并求出数列{a
n}的通项公式;
(II)令b
n=na
n,求数列{b
n}的前n项和S
n.
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