1. 6.6 – Solving Exponential Equations Using Common Logarithms. Objective: TSW solve exponential equations and use the change of base formula.

2. Change of base formula: The change of base formula allows us to change any logarithm into base 10. log b x = log x log b Example: log 8 12 =

3. To evaluate logarithms - Use the change of base formula to evaluate logarithms which are not base 10. Examples: 1.log 9 42. log 8 33. 9 – log 3 7

4. Solving equations in exponential form: 1.Get the equation in the form “b y = x” 2.Rewrite the exponential equation in logarithmic form (be sure you do not have any negative numbers within the logarithm) 3.Use the change of base formula to evaluate the logarithm. 4.Solve for x.

5. Examples: 1.2 x = 492. 8 x = 240

6. Examples: 3. 2 x+1 = 304. 67 –2 -x = 39

7. Examples: 5. 5 x +12= 676. 15 x^2 = 110

8. Homework… pgs. 519-520 #’s 1-4(all), 6-8(all), 17- 21(odds), 23-37(odds), 41-46(all)