Expert: Sherry Wallin - 12/6/2009

Question
How do you put a logarithm like log(base 6)5 into a graphing calculator?

Answer
There are two basic types of calculators, one where you put in the argument first and ones that you use just as if reads left to right. For example if you wanted to find out the sin 30deg in the first type you would have to put in 30 and then sin whereas in the 2nd type you would just press sin and then put in 30. The other observation I want to make it most calculators will only do base 10 or natural log x = ln x (where e^x is the inverse of ln x). So what you will need to do is use the change of base formula: log(base a) M = log M/log a where log is log(base 10). So in your problem you will first do the change of base from base 6 to base 10: log 5/log 6 and either in your calculator:
type I: 5 log/ 6 log or type II: log 5/log 6.

Math Prof