wl00341512 發表於 20-10-2009 19:44:03

問幾條數~求解☆★☆★☆★

本帖最後由 wl00341512 於 20-10-2009 22:32 編輯

1.
    (n+6)!
    ---------
    (n+4)!


2. nP3

3.nC2

4.n+1C3

yukating 發表於 20-10-2009 22:34:17

本帖最後由 yukating 於 20-10-2009 22:44 編輯

1. (n+6)!/(n+4)!
= (n+6)(n+5)(n+4)!/(n+4)!
= (n+6)(n+5)
2. 無教.
3. nC2
= n(n-1) / (1x2)
= 1/2(n)(n-1)
4. n+1C3
= nC3 + nC2
= n!/ + n!/
= n!/
= {n!/}
= {/2}
= {/2}
= [(n+1)(n)(n-1)]/6

[S]【YU】 發表於 20-10-2009 22:44:52

2. nP3 = n(n-1)(n-2)

3.nC2 = n(n-1)/(1x2)

4.n+1C3 = (n+1)n(n-1)/(1x2x3)

wl00341512 發表於 20-10-2009 22:49:59

本帖最後由 wl00341512 於 20-10-2009 23:39 編輯

1. (n+6)!/(n+4)!
= (n+6)(n+5)(n+4)!/(n+4)!
= (n+6)(n+5)
2. 無教.
3. nC2
= n(n-1) / (1x2)
= 1/2(n)(n-1)
4. n+1C3
= nC3 + nC2
= n!/ + n!/
= n!/
=...
yukating 發表於 20-10-2009 22:34 http://www.nakuz.com/bbs/images/common/back.gif

3同我份答案有小小唔同
多謝你解答

2. nP3 = n(n-1)(n-2)

3.nC2 = n(n-1)/(1x2)

4.n+1C3 = (n+1)n(n-1)/(1x2x3)
【YU】 發表於 20-10-2009 22:44 http://www.nakuz.com/bbs/images/common/back.gif

我想要條式..唔該

[S]【YU】 發表於 21-10-2009 19:47:34

呢個係Combination 基本既運算,無式可言

正如小數轉百分比 0.1 = 0.1 x 100% , 乜仲有式既咩?

e.g.
50C2 = (50x49)/(1x2)
100C5 = (100x99x98x97x96)/(1x2x3x4x5)

pllo19940612 發表於 9-11-2009 21:17:24

係咪M1/M2嫁= =
未見過...
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