Question

How do you use the Change of Base Formula and a calculator to evaluate the logarithm `log_4 20`?

Answer 1

I found: `log_4(20)=2.161`

Explanation:

Your formula can be used to convert, for example, to natural log or `ln`;
you can write:
`log_4(20)=ln(20)/ln(4)=` and both can be evaluated with a pocket calculator giving:
`=2.996/1.386=2.161`
Using this value you can check your result as:

`4^(2.161)=20`