若2n=㏒₂3 則 2³ⁿ+2⁻³ⁿ／2ⁿ+2⁻ⁿ =?
回答 (1)
2018-01-11 10:39 am
✔ 最佳答案
Sol2n=log2_3
2^(2n)=2^(log2_3)=3
A=[2^(3n)+2^(－3n)]/[2^n+2^(－n)]
=[2^(4n)+2^(－2n)]/[2^(2n)+1]
=(9+1/3)/(3+1)
=(27+1)/(9+3)
=28/12
=7/3
收錄日期: 2021-04-30 22:42:27
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20180111021020AAFeR2G