[解題] 排列組合
1.年級:高一
2.科目:數學
3.章節:排列組合
4.題目:擲一顆骰子3次,依次得點數為a,b,c,且a+b+c=11,有幾種情形?
5.想法:
(解答)= C(3+11-1,2) - C(3,1) * C(3+4-1,4)
= C(13,2) - 3 * C(6,2) = 78 - 45 = 33
(我解)因骰子點數1~6
=> (a+b+c=11之正整數解) - (a,b,c大於等於7)
= H(3,8) - C(3,1) * H(3,2)
= C(10,2) - 3 * C(4,2)
= 45 - 18
= 27
請問我的作法哪邊有誤嗎? 謝謝~
--
※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 123.0.35.45
※ 文章網址: http://www.ptt.cc/bbs/tutor/M.1399074478.A.720.html
推
05/03 09:52, , 1F
05/03 09:52, 1F
→
05/03 09:52, , 2F
05/03 09:52, 2F
→
05/03 10:13, , 3F
05/03 10:13, 3F
推
05/03 23:25, , 4F
05/03 23:25, 4F
→
05/03 23:25, , 5F
05/03 23:25, 5F
推
05/03 23:42, , 6F
05/03 23:42, 6F
→
05/04 00:00, , 7F
05/04 00:00, 7F
→
05/04 09:31, , 8F
05/04 09:31, 8F
推
05/09 15:23, , 9F
05/09 15:23, 9F
→
05/09 15:23, , 10F
05/09 15:23, 10F
討論串 (同標題文章)