#### Module 4 – Exponential and Logarithmic Functions

### Section 4.3 – Logarithms and Logarithmic Functions

If a site is contaminated with
a
radioactive material of half life one week so that the level of
radiation is
now ten times the safe level, how long will it be before it is safe?

This amounts to solving for the
time t in an exponential equation. It is possible to get a
rough answer by trial and error, but the ideas of this section provide
a better way.

#### What to do

- Use the Reading Guide to guide your
reading
of section 4.3 of the text. Read the following Study
Notes and Discussion, and make sure that you have absorbed the main
points by answering the questions.
- Follow the instructions regarding Further
Practice until
satisfied that you have met the Learning
Objectives for this section.
- Then proceed to the next one.