在1/n和n+1之间插入n个正数,使这n+2个正数成等比数列,则插入的n个正数之积为_.
问题描述:
在
和n+1之间插入n个正数,使这n+2个正数成等比数列,则插入的n个正数之积为______. 1 n
答
设该数列为{an},n为偶数,a1•an=a2•an-1=a3•an-2=…=an2•an2+1∴中间n个数的积为(n+1n)n2当n为奇数,a1•an=a2•an-1=a3•an-2=…=(an+12)2•中间n个数的积为(n+1n) n−12×(n+1n) 12=(n+1n)n2综上...