Exponentials
For any number b and positive integer n, we define exponentiation, i.e. b raised to the power n, as follows:
bn = b⋯b = b multiplied by itself n times
We can extend this definition to non-positive integers n as follows:
For example, 23 = 2 ∙ 2 ∙ 2 = 8, 2-3 = 1/8 and 20 = 1
Exponentiation has the following properties:
Where n > 0, we can also define = the nth root of b, i.e. the number a such that a multiplied by itself n times is b. We can extend this definition to fractional exponents as follows:
where m and n are any integers.
Without getting into all the details, ba is defined for any a, and can be calculated in Excel by b^a. E.g. 3^2.1 ≈ 10.04551 and Pi()^Pi() ≈ 36.4621 where Pi() = π = 3.1415… The properties stated above for integer exponents can be extended to any exponents, namely
Logarithms
logba, called the log of a (base b) is the number c such that bc = a. Thus, the log function is the inverse of exponentiation and has the following properties:
On this website, we use logs with base = 10 (called log base 10 and written simply as log a) and logs with base e where e is a special constant equal to 2.718282…. The log of a base e is called the natural log of a and is written as ln a.
I think the first definition, it should be:
b^n = 1/b^-n if n < 0
isn't it?
Thanks!
I don’t know why this formula wasn’t displayed correctly, but thank you very much for finding this error.
I appreciate your help in improving the website.
Charles
Last equation on left incorrect, it should be without ‘a’ raised to ‘c’ on the right hand side of the equation (corrected latex form):
\log_ba^c = c\log_ba
Thank you very much for catching this typo. I have just corrected the mistake on the referenced webpage.
I really appreciate your help in making the website more accurate and easier for people to use.
Charles