1. Lesson 2

1.8. Explore 4

Mathematics 30-2 Module 7

Module 7: Exponents and Logarithms

 

 

 

In Try This 3 you used a half-life equation to determine the time it takes for iodine-131 to decay specific amounts. View the Solving Exponential Equations presentation to see the example of how to solve the exponential equation  by writing the equation so that the bases are powers of one another and then graphing a system of equations.

 

 

This is a play button that opens Solving Exponential Equations.

 

Half-life is usually used to describe the length of time for a substance to decay to half the original amount, and can be described using the following formula:

 

 

 

In the formula, A is the final amount of the substance, A0 is the initial amount of the substance, t is the time elapsed, and h is the half-life of the substance.

 

The following example shows that it is possible to use this formula to model a decay that isn’t affected by time.



textbook

Read “Example 3” on pages 357 to 359 of the textbook to see a problem solved by using the same base and solved by graphing. Why might the textbook authors have used x instead of t in the half-life equation?

 

 

Self-Check 2
  1. Complete part a. of “Your Turn” on page 359 of your textbook. Answer
  2. Complete question 11 on page 363 of your textbook. Answer