1. Precalculus – Section 3.1

2. An exponential function is a function of the form We call b the base of the exponential function. a is a constant multiplier (think stretch/shrink). Requirements:  b greater than zero and not equal to one  x is any real number

3. The graph of the function crosses the y-axis at the point (0,a). The graph also contains the point (1,a⋅b).

4. To get more points on the graph: As you increase the value of x by 1, you multiply the previous y-value by the base b. As you decrease the value of x by 1, you divide the y-value by b.

5. …then the function grows. …then the function decays. If the base is greater than 1… If the base is less than 1…

6. Graph the exponential function. xy 01 1.3333 2.1111 3 -29

7. p. 206: 1-4, 7-10, 19-24

8. Precalculus – Section 3.1

9. A common choice for the base of an exponential function is e. e is the called the natural base because it naturally occurs in things such as:  compound interest  radioactive decay  science applications

10. The value of e to 15 decimal places… e = 2.718281828459045… Think of President Andrew Jackson (the guy on the $20 bill)! Good enough for precalculus use: 2.718281828

11. Evaluate each function. Round to 3 decimal places. 1. 2.

12. Graph the function. xf (x) 03 18.155 222.167 1.103 -20.406

13. p. 206: 5,6, 25-30 You may want to scale your graphs to fit them on the paper. Tomorrow: using exponential functions to problem solve!

14. Precalculus – Section 3.1

15. To find interest that is compounded continuously: P = principle (amount invested) r = interest rate (as a decimal) t = time (in years)

16. Find the current balance of a $7000 savings fund after 1 year if the interest is compounded continuously at 8%.

17. To find the amount of a radioactive substance that remains after t years: N = initial quantity t = time (in years) H = half-life of substance (in years)

18. A certain radioactive substance has a half-life of 825 years. Find the amount of substance that remains after 1000 years if the initial amount is 50 pounds.

19. p. 207: 51-53, 55-58