Simplify
7^n+2-7^n-1/2*7^n
Maths
2007-09-06 5:19 am
回答 (2)
2007-09-06 5:25 am
✔ 最佳答案
7n+2-7n-1/2(7n )= 7n ( 72 ) – 7n ( 7-1 ) / 2 ( 7n )
= 7n ( 49 – 1 / 7 ) / 2 ( 7n )
= ( 49 – 1 / 7 ) / 2
= 171 / 7
2007-09-05 21:26:56 補充：
Reminder: a^ ( m + n ) = ( a^m )( a^n )
參考: My Maths Knowledge
2007-09-06 7:58 am
你唔加括號其實唔知加減後個數係咪跟住指數
我估係
7^(n+2) - 7^(n-1)/(2*7^n)
=7^n*7^2 - 7^(n-1-n)/2
=49*7^n - (7^-1)/2
=49*7^n - 1/14
我估係
7^(n+2) - 7^(n-1)/(2*7^n)
=7^n*7^2 - 7^(n-1-n)/2
=49*7^n - (7^-1)/2
=49*7^n - 1/14
收錄日期: 2021-04-13 13:20:20
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070905000051KK04136