Skill 15: Converting Between Exponential and Logarithmic Forms

Have SAT Practice Set 3 out on your desk.

Revisiting Exponents

Important Property #1:

Examples:a) b) c)

Revisiting Exponents

Important Property #2:

Examples:a) b) c)

Revisiting Exponents

Important Property #3:

Examples:a) b) c)

You Try:

1. 2. 3.

Why use a logarithm?

• Sound scales (decibels)• Earthquake measurements

(Richter scale)• Musical scales• pH measurements

Discovering Logarithms

What is a logarithm?

• A logarithm is another way of describing the exponent in an equation.

2 is the logarithm for the base 6 that gives 36 as the answer.

If

Converting Equations Between Logarithmic and Exponential Forms

Example #2: Write in logarithmic form:

Converting Equations Between Logarithmic and Exponential Forms

Example #3: Write in exponential form:

You Try: On Your Whiteboard

1. Write in logarithmic form:

2. Write in exponential form:

Evaluating a Logarithmic Expression

Example #6:a.

b.

c.

Evaluating a Logarithmic Expression

Example #6:d. e. f.

You Try:

1. 2. 3. 4.

Solving Simple Logarithmic Equations

Example #5: Solve

Example #6: Solve

Solving Simple Logarithmic Equations

Example #7:Solve .

You Try:

Solve:

Logarithm “War”

• Expectations– On-task– Stuck? Ask your partner, then ask me by raising your hand.

Exit Quiz1. Convert into logarithmic form:

2. Convert into exponential form:

3. Evaluate the logarithm:

4. Solve the equation: