1.如果某一種聲音的音量增加了10dB該聲音的強度是原來的多少倍？
解下列對數方程:
2.log(x+2)=log(x-2)+2
3.log(x-4)=log(3x-10)+log1/5
中四數學<對數函數>三題
2008-11-28 7:42 pm
回答 (1)
2008-11-28 8:19 pm
✔ 最佳答案
1.Based on the formula log I/Io = x Bel.
Now x = 10dB = 1 Bel, therefore,
log I/Io = 1
I/Io = 10
so I = 10Io, that is sound intensity is 10 times the original intensity.
2.
log(x + 2) = log(x -2) + 2
log (x +2) = log (x-2) + log 100
log (x+2) = log 100(x-2)
x +2 = 100(x-2)
x + 2 = 100x - 200
99x = 202
x = 202/99.
3.
log(x -4) = log(3x-10) + log (1/5)
log ( x -4) = log [(3x-10)/5]
x - 4 = (3x -10)/5
5x - 20 = 3x - 10
2x = 10
x = 5.
收錄日期: 2021-04-25 22:39:52
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20081128000051KK00359