1. Lesson 10.4Common Logarithms Common Logarithm:base 10 logarithms (without subscript 10) Example 1Finding Common Logs & Change of Base A) B)C).4771 -.69902.2619

2. Example 2 A)The amount of energy E, in ergs that an earthquake releases is related to the Richter scale magnitude M given above. The Chilean earthquake of 1960 measured 8.5 on the Richter scale, how much energy was released? B)The Sumatran earthquake of 2005 measured 9 on the Richter scale. How much energy was released?

3. Example 3Solving Exponential Equations a) b) c) d)

4. Example 4 a) b)

5. Example 4 c) d)

6. Practice