一條數學問題

👨🏻‍🏫 學術台數學

Jacky

2007-07-22 8:24 pm

3^(n-1)分之3^(n+1)=?
點計?

回答 (3)

cml327

2007-07-22 8:39 pm

✔ 最佳答案

3^(n-1)=3^n÷3^1=3^n/3
3^(n+1)=3^nx3^1=3^nx3

3^(n-1)分之3^(n+1)
=3^nx3^1÷(3^n/3^1)
=3^n(3)x3/3^n
=3x3 <--3^n約左
=9

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Heung Lin

2007-07-22 9:22 pm

3^(n-1)分之3^(n+1)
=3^n * 1/3 分之3^n * 3 (將括號拆走)
=(3^n * 3 * 3) / 3^n (將1/3 調到分母)
=3*3(將3^n 約走)
=9

參考: me

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Cecilia

2007-07-22 8:35 pm

3^(n+1) / 3^(n-1) = 3^n * 3 / 3^n * 3^-1
= ( 3^n / 3^n) * ( 3 * 3)
= 9

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