u have a strange name

anyway

when u did not write the base it is 10

in general

if u do not know what is the logarithm this is an example

suppose then

so

to find

let

so

second one same as the first one

Results 1 to 9 of 9

- September 7th 2010, 05:44 AM #1

- Joined
- Aug 2010
- From
- Singapore
- Posts
- 93

- September 7th 2010, 05:53 AM #2

- September 7th 2010, 06:09 AM #3

- Joined
- Aug 2010
- From
- Singapore
- Posts
- 93

- September 7th 2010, 06:13 AM #4

- Joined
- Aug 2010
- From
- Singapore
- Posts
- 93

- September 7th 2010, 07:56 AM #5

- Joined
- Apr 2005
- Posts
- 17,283
- Thanks
- 2139

Specifically, or "logarithm to base a of x" is defined as the "inverse function" to . That is, each "undoes" the other: and .

Your "lg" is an abbreviation for the "common logarithm" or "logarithm base 10", which is the inverse to . for all x (and so for x= 5 ). for all positive x (and so for x= 5 .

"ln" is an abbreviation for the "natural logarithm" or "logarithm base e" (e is about 2.718...) which is inverse to . for all x (and so for x= 5 . for all positive x (and so for x= 5 .)

(Note the difference between "for all x" and "for positive x". The function " is only defined for positive a and always has a positive value- that is, is a function from the set of all real numbers to the set of all**positive**real numbers. It's inverse, , is a function from the set of all positive real numbers to the set of real numbers.)

- September 7th 2010, 09:01 AM #6

- Joined
- Aug 2010
- From
- Singapore
- Posts
- 93

- September 7th 2010, 09:06 AM #7

- September 7th 2010, 01:01 PM #8

- Joined
- Aug 2010
- From
- Singapore
- Posts
- 93

- September 7th 2010, 01:27 PM #9