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(1-1/2²)(1-1/3²)(1-1/4²)(1-1/5²)······[1-1/(n+1)²]利用平方差公式计算
题目详情
(1-1/2²)(1-1/3²)(1-1/4²)(1-1/5²)······[1-1/(n+1)²] 利用平方差公式计算
▼优质解答
答案和解析
原式=(1-1/2)(1+1/2)(1-1/3)(1+1/3)……[1-1/(n+1)][1+1/(n+1)]
=(1/2)(3/2)(2/3)(4/3)……n/(n+1)][(n+2)/(n+1)]
中间约分
=(1/2)[(n+2)/(n+1)]
=(n+2)/(2n+2)
=(1/2)(3/2)(2/3)(4/3)……n/(n+1)][(n+2)/(n+1)]
中间约分
=(1/2)[(n+2)/(n+1)]
=(n+2)/(2n+2)
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