# Math Help - change of base formula?

1. ## change of base formula?

Use the change of base formula then a calculator to evaluate
so i did change of base I think>? 9 ^42.11 then used the calculator and got 1.52?

2. Originally Posted by rj2001
Use the change of base formula then a calculator to evaluate
so i did change of base I think>? 9 ^42.11 then used the calculator and got 1.52?
What are you asking? How to use the change of base formula to calculate $\log_9(42.11)$?

By the change of base theorem this is equal to

$\frac{\log(42.11)}{\log(9)}=\frac{\ln(42.11)}{\ln( 9)}=\frac{\lg(42.11)}{\lg(9)}$

3. It says Use change of base formula and a calculator to evaluate the following Log round your answer to 3 dec places

1)Log base 9 42.11

2)Log base5 3

4. Originally Posted by rj2001
It says Use change of base formula and a calculator to evaluate the following Log round your answer to 3 dec places

1)Log base 9 42.11

2)Log base5 3
So do exactly what I showed you. And do the same for number two except replace 42.11 with 3 and 9 with 5