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8.1 Understanding Logarithms.notebook 1 Chapter 8: Logarithmic Functions

Chapter 8: Logarithmic Functions · PDF file08.06.2015 · 8.1 Understanding Logarithms.notebook 4 3. Complete the following table: Function Domain Range x­intercepts y­intercept

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Page 1: Chapter 8: Logarithmic Functions · PDF file08.06.2015 · 8.1 Understanding Logarithms.notebook 4 3. Complete the following table: Function Domain Range x­intercepts y­intercept

8.1 Understanding Logarithms.notebook

1

Chapter 8: Logarithmic Functions

Page 2: Chapter 8: Logarithmic Functions · PDF file08.06.2015 · 8.1 Understanding Logarithms.notebook 4 3. Complete the following table: Function Domain Range x­intercepts y­intercept

8.1 Understanding Logarithms.notebook

2

Chapter 8

8.1  Understanding LogarithmsPages 372 ­ 382

Investigating Logarithmic Functions:1.  Complete the following table using             and sketch on the axis provided.

x y 

­2

­1

0

1

2

Page 3: Chapter 8: Logarithmic Functions · PDF file08.06.2015 · 8.1 Understanding Logarithms.notebook 4 3. Complete the following table: Function Domain Range x­intercepts y­intercept

8.1 Understanding Logarithms.notebook

3

2. Complete the table for the inverse of              and sketch on the previous axis.

x y 

Page 4: Chapter 8: Logarithmic Functions · PDF file08.06.2015 · 8.1 Understanding Logarithms.notebook 4 3. Complete the following table: Function Domain Range x­intercepts y­intercept

8.1 Understanding Logarithms.notebook

4

3. Complete the following table:

Function Domain Range x­intercepts y­intercept Asymptote

Inverse

4. Write the equation for the inverse in terms of y.

Page 5: Chapter 8: Logarithmic Functions · PDF file08.06.2015 · 8.1 Understanding Logarithms.notebook 4 3. Complete the following table: Function Domain Range x­intercepts y­intercept

8.1 Understanding Logarithms.notebook

5

Exponential Function:

Logarithmic Function:  NOTE:  Logarithms are exponents.

Inverse in exponential form: 

**  The exponent, y,  to which c must be raised to equal x. 

Page 6: Chapter 8: Logarithmic Functions · PDF file08.06.2015 · 8.1 Understanding Logarithms.notebook 4 3. Complete the following table: Function Domain Range x­intercepts y­intercept

8.1 Understanding Logarithms.notebook

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Natural logarithm  ­  a logarithm with base e.  ­  ln is used instead of log.

Example: 

logarithmic function ­  a function of the form                   where c > 0 and 

common logarithm  ­  a logarithm with base 10.­  usually not written.­  calculators only work in base 10.

Example:

Page 7: Chapter 8: Logarithmic Functions · PDF file08.06.2015 · 8.1 Understanding Logarithms.notebook 4 3. Complete the following table: Function Domain Range x­intercepts y­intercept

8.1 Understanding Logarithms.notebook

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Examples:1. Rewrite the following logarithms in exponential form:

a)    log216 = y b)    log264 = y c)     log10100 = y

d)     log381 = y e)     log2n = 5 f)     logb49 = 2

Page 8: Chapter 8: Logarithmic Functions · PDF file08.06.2015 · 8.1 Understanding Logarithms.notebook 4 3. Complete the following table: Function Domain Range x­intercepts y­intercept

8.1 Understanding Logarithms.notebook

8

2. Express in logarithmic form:

a)    62 = 36 c)     4x = n

d)     35 = 243    

Page 9: Chapter 8: Logarithmic Functions · PDF file08.06.2015 · 8.1 Understanding Logarithms.notebook 4 3. Complete the following table: Function Domain Range x­intercepts y­intercept

8.1 Understanding Logarithms.notebook

9

Example 1Page 374

Evaluating a LogarithmEvaluate the following:

Page 10: Chapter 8: Logarithmic Functions · PDF file08.06.2015 · 8.1 Understanding Logarithms.notebook 4 3. Complete the following table: Function Domain Range x­intercepts y­intercept

8.1 Understanding Logarithms.notebook

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Example 1:  Your TurnPage 374

Evaluate:

Answer

Page 11: Chapter 8: Logarithmic Functions · PDF file08.06.2015 · 8.1 Understanding Logarithms.notebook 4 3. Complete the following table: Function Domain Range x­intercepts y­intercept

8.1 Understanding Logarithms.notebook

11

Helpful Properties of logarithms:

­  since logarithms and exponents are inverse mathematical operations, they undo each other

Page 12: Chapter 8: Logarithmic Functions · PDF file08.06.2015 · 8.1 Understanding Logarithms.notebook 4 3. Complete the following table: Function Domain Range x­intercepts y­intercept

8.1 Understanding Logarithms.notebook

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Example 2Page 375 Determining an unknown expression in logarithmic form:

Determine the value of x:

Page 13: Chapter 8: Logarithmic Functions · PDF file08.06.2015 · 8.1 Understanding Logarithms.notebook 4 3. Complete the following table: Function Domain Range x­intercepts y­intercept

8.1 Understanding Logarithms.notebook

13

Example 2:  Your TurnPage 375

Determine the value of x:

Answer