1

Calculators can evaluate base 10 logarithms.

If you are asked to evaluate a logarithm without a base 10, the “Change of Base”

theorem is useful.

Examples: 1.

2log 17Evaluate

Other Useful Properties

1. log 1b b

Proof:

Change of Base Theorem

2

log3: log 3

log 2Example

2

2. log y

b b y

Proof:

3.

logb ab a

Proof:

Try On Your Own

A) 2

2log 4y B) 5log 4

125 x

Assignment: Exercise 23 #1-13, 15, 16, 18, 20.

You will have time on Monday as well