1. 6.5 Applications of Common Logarithms
Objectives: Define and use the common logarithmic
function to solve exponential and logarithmic equations.
Evaluate logarithmic expressions by using the
change-of-base formula.
Standard: N. Solve exponential equations.

2. Warm Up:
1.51
0.25
-2.30

3. The base 10 logarithm is called the common logarithm.
In general, logarithmic functions are used
to assign large values in the domain to
small values in the range. x 10
100
1000
10,000
100,000 …
y = log x 1 2 3 4 5

4. Recall from lesson 2.7 that the graph of y = a*f(x)
is the graph of y = f(x) stretched by a factor of a.
Therefore the graph of y = 10 log x is the graph
of y = log x stretched by a factor of 10.

6. The running vacuum cleaner is about
times as loud as the threshold of hearing.

10. You can use the change-of-base formula to change a logarithmic expression of any base to base 10 so that you can use the LOG key on your calculator.

13. p. 389 #10-16 even

14. p. 390: #28-34 Even

15. Homework: Practice 6.5
Chapter 6 Test FRIDAY!