數學題(送分題)
回答 (26)
2007-03-30 8:41 pm
✔ 最佳答案
499500 
2007-03-31 12:37 am
499500
2007-03-31 12:16 am
1+2+3+4...................+999=?
=499500
=499500
2007-03-30 8:42 am
一定係 499500
2007-03-30 6:58 am
......等於499500....
2007-03-30 3:40 am
1+2+3+4...................+999
=((1+999)x999)/2
=(1000x999)/2
=499500
=((1+999)x999)/2
=(1000x999)/2
=499500
2007-03-30 3:04 am
Let S = 1+2 +3 + ...+997+998+999 -----(A)
S = 999+998+997 +...3+2+1 ----------(B)
(A) + (B) 2S = (1+999) + (2+998) +(3+997) .... + (997+3) + (998+2) + (999+1)
= 1000 + 1000 + 1000 + .... + 1000 + 1000 + 1000
= (1000)(999)
S = (1000)(999)/2
=499500
Therefore 1+2 +3 + ...+997+998+999 =499500
S = 999+998+997 +...3+2+1 ----------(B)
(A) + (B) 2S = (1+999) + (2+998) +(3+997) .... + (997+3) + (998+2) + (999+1)
= 1000 + 1000 + 1000 + .... + 1000 + 1000 + 1000
= (1000)(999)
S = (1000)(999)/2
=499500
Therefore 1+2 +3 + ...+997+998+999 =499500
2007-03-30 1:04 am
=499500
2007-03-30 12:57 am
1+2+3+4...................+999=499500
= (999/2)[2*1+(999-1)*1]
= (999/2)(1000)
= (999*1000)/2
= 999000/2
= 499500
對吧?
= (999/2)[2*1+(999-1)*1]
= (999/2)(1000)
= (999*1000)/2
= 999000/2
= 499500
對吧?
參考: me....................
2007-03-30 12:52 am
1+2+3+4...................+999=499500
2007-03-30 12:51 am
=499500
收錄日期: 2021-04-12 22:16:20
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070329000051KK02171