已知数列bn=[1/(6n+3)]*[1/(6n-3)]求bn的前n项和

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已知数列bn=[1/(6n+3)]*[1/(6n-3)]求bn的前n项和
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已知数列bn=[1/(6n+3)]*[1/(6n-3)]求bn的前n项和
已知数列bn=[1/(6n+3)]*[1/(6n-3)]求bn的前n项和

已知数列bn=[1/(6n+3)]*[1/(6n-3)]求bn的前n项和
bn=1/6*[1/(6n-3)-1/(6n+3)]------->6bn=1/(6n-3)-1/(6n+3)
设前n项和为S,则
S=b1+b2+……+bn----------------->6S=6b1+6b2+……+6bn=(1/3-1/9)+(1/9-1/15)+……+[1/(6n-3)-1/(6n+3)]=1/3-1/(6n+3)
S=1/18-1/6*(6n+3)

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