关于4T9的百科

• 等比数列{an}是递减数列,其前n项的积为Tn,若T13＝4T9,则a8·a15等于(   )A.±2    ...

• 问题详情：等比数列{an}是递减数列,其前n项的积为Tn,若T13＝4T9,则a8·a15等于(   )A.±2                 B.±4                 C.2                     D.4【回答】解析:∵{an}是递减数列,则a1＞0,0＜q＜1或a1＜0,q＞1...
• 2022-08-1817733