有冇人可解釋以下2條數學題???

2014-02-09 6:27 am
有冇人可解釋以下2條數學題???

0,6,24,60,120





6,24,60,120,210

回答 (2)

2014-02-09 6:36 am
✔ 最佳答案
數列一

0, 6, 24, 60, 120, ...

留意:
0 = 0 × 1 × 2 = 1 - 1 = 1³ - 1
6 = 1 × 2 × 3 = 8 - 2 = 2³ - 2
24 = 2 × 3 × 4 = 27 - 3 = 3³ - 3
60 = 3 × 4 × 5 = 64 - 4 = 4³ - 4
120 = 4 × 5 × 6 = 125 - 5 = 5³ - 5

因此,可以推測下一項是 5 × 6 × 7 = 210,
再下一項是 6 × 7 × 8 = 336。

也很易看出通項 (general term) 是 (n-1)n(n+1) = n³ - n

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數列二

6, 24, 60, 120, 210, ...

留意:
6 = 1 × 2 × 3
24 = 2 × 3 × 4
60 = 3 × 4 × 5
120 = 4 × 5 × 6
210 = 5 × 6 × 7

因此,可以推測下一項是 6 × 7 × 8 = 336,
再下一項是 7 × 8 × 9 = 504。

也很易看出通項 (general term) 是 n(n+1)(n+2) = n³ + 3n² + 2n


2014-02-08 23:35:20 補充:
郭老師太過獎啦~

大家都要繼續努力!

☆ヾ(◕‿◕)ノ
2014-02-09 7:24 am
閣下對數字非常敏感,佩服!


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