Chapter 4 – Exponential and Logarithmic Functions 4.1 - Exponential Functions.

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Section 4.1 Exponential Functions Chapter 4 – Exponential and Logarithmic Functions 4.1 - Exponential Functions

Transcript of Chapter 4 – Exponential and Logarithmic Functions 4.1 - Exponential Functions.

Page 1: Chapter 4 – Exponential and Logarithmic Functions 4.1 - Exponential Functions.

4.1 - Exponential Functions

Section 4.1 Exponential Functions

Chapter 4 – Exponential and Logarithmic Functions

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4.1 - Exponential Functions

Exponential Functions

What is an exponential function?

An exponential function has its variable in the exponent.

It may be used to model rapidly increasing or decreasing situations such as population growth, growth of epidemics, radioactive decay, cooling or heating of objects, etc.

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4.1 - Exponential Functions

Review – Laws of Exponents

Simplify the following:

2 3

11

7

13

23

64

42 3

a a

a

a

a

a

a

a b

2 7

19

17

24

27

32

53 4

3 3

4

4

2

2

6

2

x

x y

0

6

0

0

3

3

3

10

1

2

0.5

a

a

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4.1 - Exponential Functions

EvaluatingAnswer the question below.

In college, we study large volumes of information that, unfortunately, we do not often retain for very long. The function

describes the percentage of information that a person can be expected to remember x weeks after learning it.

0.5( ) 80 20xf x e

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4.1 - Exponential Functions

Evaluating0.5( ) 80 20xf x e

1.) Let x = 0 and give the value of f (0).

2.) Let x = 1 and determine the value of f (1)

accurate to the nearest ten-thousandth.

3.) Let x = 52 and determine the value of f (52) accurate to the nearest thousandth.

f (0)= 100

f (1)= 68.5225

f (52)= 20

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4.1 - Exponential Functions

Exponential Functions

The exponential function with base a is defined for all real numbers x by

where a > 0 and a 1.

xf x a

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4.1 - Exponential Functions

Exponential Functions

What does an exponential function look like?

What is its domain and range?

Does it increase or decrease or both?

Does it have vertical or horizontal asymptotes?

( ) 2xf x

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4.1 - Exponential Functions

Exponential Functions

What does an exponential function look like?

What is its domain and range?

Does it increase or decrease or both?

Does it have vertical or horizontal asymptotes?

( ) 2 xf x

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4.1 - Exponential Functions

Graphs of Exponential Functions

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Transformations of FunctionsWe will now see how to graph certain functions by

looking at the basic graphs of exponential functions and applying the shifting and reflecting transformations.

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4.1 - Exponential Functions

ExampleUse the graph of to sketch the graph of

each function. 2xf x

31. ( ) 2

2. ( ) 2 3

3. ( ) 2

x

x

x

j x

k x

l x

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4.1 - Exponential Functions

Example – pg. 308 # 19 & 20Find the exponential function f (x) = ax whose graph

is given.

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ApplicationExponential functions occur in calculating

compound interest.

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Compounding – Key Words

Compounding

n

Annual 1

Semiannual 2

Quarterly 4

Monthly 12

Daily 365

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4.1 - Exponential Functions

Example – pg. 309 # 52

If $2500.00 is invested at an interest rate of 2.5%, compounded daily, find the value of the investment after the given amount of years.

a) 2 years

b) 3 years

c) 6 years

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4.1 - Exponential Functions

Example – pg. 309 #56

Find the present value of $100,000 if interest is paid at a rate of 8% per year, compounded monthly, for 5 years.