Challenging Maths[20點!!!!!!]

2007-10-23 12:17 am
(2x5(n次方))(2次方) - 5(2n次方)
-------------------------------------------------
3 x 5(n次方)

回答 (1)

2007-10-23 12:34 am
✔ 最佳答案
[ (2*5^n)^2 - 5^2n ] / 3*5^n
= (4*5^2n - 5^2n) / 3*5^n
= 5^2n(4-1) / 3*5^n
= 3*5^2n / 3*5^n
= 5^2n / 5^n
= 5^(2n-n)
= 5^n

2007-10-22 16:35:44 補充:
5^n 的二次方即是 5^2n第三行...5^2n 是 common factor 所以可以抽出來5^2n / 5^n 是次方相減所以得到 5^n 為最後答案


收錄日期: 2021-04-13 19:02:54
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20071022000051KK01663

檢視 Wayback Machine 備份