Change of Base Formula
Pronunciation: /tʃeɪndʒ ʌv beɪs/ ?
The change of base formula is used to change the
The change of base formula is
When logarithms were first invented, there were no calculators. Mathematicians and
astronomers used books published with tables of logarithms. Each table had exactly one
base. To find a logarithm with another base, they used the change of base formula.
Today, most calculators and math based computer programs have logarithms in two
bases: base 10 and base e. To find a logarithm in any other base, one
must use the change of base formula.
|Figure 1: Change of base mnemonic.||
- Solve log24.
- Solve log522.
- Bettinger, Alvin K. and Englund, John A.. Algebra and Trigonometry, pg 113-114. International Textbook Company, January 1963. (Accessed: 2010-01-11). http://www.archive.org/stream/algebraandtrigon033520mbp#page/n130/mode/1up/search/base.
- McAdams, David. Logarithm. allmathwords.org. All Math Words Encyclopedia. Life is a Story Problem LLC. 2009-03-12. http://www.allmathwords.org/article.aspx?lang=en&id=Logarithm.
- Staple, Elizabeth. Log Rules - Change of Base Formula. purplemath.com. Purplemath. 1999-01-01. http://www.purplemath.com/modules/logrules4.htm.
Cite this article as:
Change of Base Formula. 2010-01-11. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/c/changeofbaseformula.html.
2010-01-11: Added "References", "More Information" (McAdams, David.
2008-11-25: Initial version (McAdams, David.