这是数列题吧。|n/(2n十1)-1/2|=|2n/2*(2n十1)- (2n十1)/2*(2n十1)|=|(2n-(2n十1))/2*(2n十1)|=|(2n-2n-1)/2*(2n十1)|=|-1/2*(2n十1)|=|1/2*(2n十1)|=1/2*(2n十1)
望采纳，谢谢
