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6.4 Graphs of Logarithmic Functions

Domain restrictions forced by the argument, the vertical asymptote, and curves mirrored from their exponential partners.

Algebra and Trigonometry 2e, 6.4 Graphs of Logarithmic Functions

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30 exercises

Identifying the Domain of a Logarithmic Shift

What is the domain of f(x)= log 2 (x+3)? f \left(x\right) = \log_{2} \left(x + 3\right) ?

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6.4 Exercise 16

What is the domain of f(x)= log 5 (x−2)+1? f \left(x\right) = \log_{5} \left(x - 2\right) + 1 ?

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Identifying the Domain of a Logarithmic Shift and Reflection

What is the domain of f(x)=log(5−2x)? f \left(x\right) = \log \left(5 - 2 x\right) ?

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6.4 Exercise 18

What is the domain of f(x)=log(x−5)+2? f \left(x\right) = \log \left(x - 5\right) + 2 ?

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Approximating the Solution of a Logarithmic Equation

Solve 4ln( x )+1=−2ln( x−1 ) 4 \ln \left(x\right) + 1 = - 2 \ln \left(x - 1\right) graphically. Round to the nearest thousandth.

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6.4 Exercise 32

Solve 5log( x+2 )=4−log( x ) 5 \log \left(x + 2\right) = 4 - \log \left(x\right) graphically. Round to the nearest thousandth.

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Finding the Vertical Asymptote of a Logarithm Graph

What is the vertical asymptote of f(x)=−2 log 3 (x+4)+5? f \left(x\right) = −2 \log_{3} \left(x + 4\right) + 5 ?

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6.4 Exercise 34

What is the vertical asymptote of f(x)=3+ln(x−1)? f \left(x\right) = 3 + \ln \left(x - 1\right) ?

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6.4 Exercise 37

The inverse of every logarithmic function is an exponential function and vice-versa. What does this tell us about the relationship between the coordinates of the points on the graphs of each?

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6.4 Exercise 39

What type(s) of translation(s), if any, affect the domain of a logarithmic function?

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6.4 Exercise 41

Does the graph of a general logarithmic function have a horizontal asymptote? Explain.

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6.4 Exercise 43

State the domain and range of the function.

h(x)=ln( 1 2 −x ) h \left(x\right) = \ln \left(\frac{1}{2} - x\right)

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6.4 Exercise 45

State the domain and range of the function.

h(x)=ln( 4x+17 )−5 h \left(x\right) = \ln \left(4 x + 17\right) - 5

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6.4 Exercise 47

State the domain and the vertical asymptote of the function.

f(x)= log b (x−5) f \left(x\right) = \log_{b} \left(x - 5\right)

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6.4 Exercise 49

State the domain and the vertical asymptote of the function.

f(x)=log(3x+1) f \left(x\right) = \log \left(3 x + 1\right)

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6.4 Exercise 51

State the domain and the vertical asymptote of the function.

g(x)=−ln(3x+9)−7 g \left(x\right) = - \ln \left(3 x + 9\right) - 7

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6.4 Exercise 53

State the domain, vertical asymptote, and end behavior of the function.

f(x)=log( x− 3 7 ) f \left(x\right) = \log \left(x - \frac{3}{7}\right)

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6.4 Exercise 55

State the domain, vertical asymptote, and end behavior of the function.

g(x)=ln( 2x+6 )−5 g \left(x\right) = \ln \left(2 x + 6\right) - 5

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6.4 Exercise 57

State the domain, range, and x- and y-intercepts, if they exist. If they do not exist, write DNE.

h(x)= log 4 ( x−1 )+1 h \left(x\right) = \log_{4} \left(x - 1\right) + 1

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6.4 Exercise 59

State the domain, range, and x- and y-intercepts, if they exist. If they do not exist, write DNE.

g(x)=ln( −x )−2 g \left(x\right) = \ln \left(- x\right) - 2

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6.4 Exercise 61

State the domain, range, and x- and y-intercepts, if they exist. If they do not exist, write DNE.

h(x)=3ln( x )−9 h \left(x\right) = 3 \ln \left(x\right) - 9

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6.4 Exercise 63

f(x)=ln(x) f \left(x\right) = \ln \left(x\right)

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6.4 Exercise 65

h(x)= log 5 ( x ) h \left(x\right) = \log_{5} \left(x\right)

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6.4 Exercise 67

f(x)= log 1 3 ( x ) f \left(x\right) = \log_{\frac{1}{3}} \left(x\right)

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6.4 Exercise 69

h(x)= log 3 4 ( x ) h \left(x\right) = \log_{\frac{3}{4}} \left(x\right)

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6.4 Exercise 75

g(x)=− log 4 ( x+2 ) g \left(x\right) = - \log_{4} \left(x + 2\right)

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6.4 Exercise 87

Use a graphing calculator to find approximate solutions to each equation.

log( x−1 )+2=ln( x−1 )+2 \log \left(x - 1\right) + 2 = \ln \left(x - 1\right) + 2

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6.4 Exercise 89

Use a graphing calculator to find approximate solutions to each equation.

ln( x−2 )=−ln( x+1 ) \ln \left(x - 2\right) = - \ln \left(x + 1\right)

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6.4 Exercise 91

Use a graphing calculator to find approximate solutions to each equation.

1 3 log( 1−x )=log( x+1 )+ 1 3 \frac{1}{3} \log \left(1 - x\right) = \log \left(x + 1\right) + \frac{1}{3}

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6.4 Exercise 93

Explore and discuss the graphs of f(x)= log 1 2 ( x ) f \left(x\right) = \log_{\frac{1}{2}} \left(x\right) and g(x)=− log 2 ( x ). g \left(x\right) = - \log_{2} \left(x\right) . Make a conjecture based on the result.

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Adapted from College Algebra © 2021 Rice University. Licensed under CC BY 4.0. Sources: College Algebra 2e, Algebra and Trigonometry 2e, Precalculus 2e, College Algebra with Corequisite Support 2e. Imported at revision 4922e46.