數學題(微分)

如下：

圖片參考：http://s146.photobucket.com/albums/r254/kwanhimshek/hk_d_log_10.gif

(http://s146.photobucket.com/albums/r254/kwanhimshek/hk_d_log_10.gif)



2009-08-03 11:04:26 補充：
點解Yahoo d 貼圖會咁差勁?

2009-08-06 00:01:36 補充：
更正:
第四行的應該是
(ln x)' * 1/(ln 10)

Most important is to understand the rule on change of base:
log x to the base a = log x to the base b/log a to the base b.
Now a = 10, b = e
so log x to the base 10 = log x to the base e / log 10 to the base e
that is log x = ln x / ln 10
so d(log x) = (1/ln 10) d(ln x) = (1/ln 10)(1/x).