1. Warm Up Solve 9 2x = 45.

2. 7.7 – Base e and Natural Logarithms

3. Natural Base (base e) f(x) = e x and f(x) = e -x If graphed, they follow rules of exponential growth or decay.

4. Remember… Log b x and b x are inverses of each other Since we are working with e x in this section, it’s inverse will be log e x. – This is the natural logarithm – Usually written as ln x

5. Example 1: A. Write an equivalent logarithmic equation for e x = 23. B. What is e 4 = x in logarithmic form?

6. Example 2: A. Write ln 25 = x in exponential form. B. Write ln 47 = x in exponential form.

7. Example 3: Condense A. Write 4 ln 3 + ln 6 as a single logarithm. B. Write 2 ln 3 + ln 4 + ln y as a single logarithm.

8. Example 4a: Solve Base e Equations Solve 3e –2x + 4 = 10. Round to the nearest ten-thousandth.

9. Example 4b: Solve Base e Equations Solve the exponential equation. Round to the nearest ten-thousandth. 2e –2x + 5 = 15

10. Example 5a: Solve Natural Log Equations Solve the logarithmic equation. Round to the nearest ten-thousandth. 2 ln 5x = 6

11. Example 5b: Solve Natural Log Equations Solve the logarithmic equation. Round to the nearest ten-thousandth. 3 ln 6x = 12

12. Example 6a: Solve Natural Log Inequalities Solve the logarithmic inequality. Round to the nearest ten-thousandth. ln (3x + 1) 2 > 8

13. Example 6b: Solve Natural Log Inequalities Solve the logarithmic inequality. Round to the nearest ten-thousandth. ln (4x – 2) > 7

15. Example 7: A. Suppose you deposit $700 into an account paying 3% annual interest, compounded continuously. What is the balance after 8 years?

16. Example 7: B. Suppose you deposit $700 into an account paying 2.4% annual interest, compounded continuously. How long will it take for the balance in your account to reach at least $1200?

17. Example 7: C. Suppose you deposit money into an account paying 3% annual interest, compounded continuously. How much would have to be deposited in order to reach a balance of $1950 after 10 years?