(3^(n+1)-3^(n-1))/2*3^n
更新1:
I dont understand ! plz asked easily
How to do this ???? F.3 MATH QU
回答 (2)
2008-08-08 5:23 am
I dont understand ! plz asked easily
2008-08-07 11:15 pm
(3^(n+1)-3^(n-1))/(2*3^n)
=3^(n-1)*(3^2-1)/2*3^n
=3^(n-1-n)*8/2
=4/3
=3^(n-1)*(3^2-1)/2*3^n
=3^(n-1-n)*8/2
=4/3
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https://hk.answers.yahoo.com/question/index?qid=20080807000051KK01580