數學難題一問(20分)急!

2008-04-08 3:24 am
解log 1+log 2+log 3+ log4.......+ log 100
without using a caculator.

log 1+ log 2+log 3.......+log 100=log 100!
不可使用計算機,回答請附上步驟......thx

回答 (2)

2008-04-08 7:15 am
✔ 最佳答案
log 1 + log 2 + log 3 + ... + log 99 + log100
= log (1)(2)(3)(4)(...)(99)(100) (因為log m + log n = log mn)
= log 100! (因為1x2x3x4x5...x(n-2)(n-1)n = n!)

log1 = 0
log 10 = 1
log 100 = 2
所以log 1 - log 100入面每一個既值都係0-2中間
所以
91 < log 1 + log 2 + log 3 + ... + log 99 + log100 < 189
自己計埋落去啦 = =

2008-04-11 00:44:09 補充:
91 < log 1 + log 2 + log 3 + ... + log 99 + log100 < 189
2008-04-08 11:54 am
log 1+log 2+log 3+ log4.......+ log 100
=log 1*2*3*......*100
(log m+log n=log mn)
=log (100-99)*(100-98)*(100-97)*...*100
=log 100*(100-1)*(100-2)*(100-3)*...*(100-99)
[n!=n(n-1)(n-2)(n-3)........]
=log 100!


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