P.5 Assess Your Understanding

Concepts and Vocabulary

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The graph of every exponential function \(f( x) =a^{x}\), \(a>0\) and \(a\neq 1\), passes through three points: _____, _____, and _____.

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True or False  The graph of the exponential function \(f( x) =\left( \dfrac{3}{2}\!\right) ^{\!\!\!x}\) is decreasing.

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If \(3^{x}=3^{4}\), then \(x=\) _____.

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If \(4^{x}=8^{2}\) then \(x=\) _____.

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True or False  The graphs of \(y=3^{x}\) and \(y=\left( \dfrac{1}{3}\!\right) ^{\!\!\!x}\) are symmetric with respect to the line \(y=x\).

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True or False  The range of the exponential function \( f(x) = a^{x}\), \(a>0\) and \(a\neq 1\), is the set of all real numbers.

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The number \(e\) is defined as the base of the exponential function \(f\) whose tangent line to the graph of \(f\) at the point \( ( 0,1) \) has slope _____.

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The domain of the logarithmic function \(f( x) =\log _{a}x\) is _____.

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The graph of every logarithmic function \(f( x) =\log _{a}x\), \(a>0\) and \(a\neq 1\), passes through three points: _____, _____, and _____.

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Multiple Choice  The graph of \(f( x) =\log _{2}x\) is [(a) increasing, (b) decreasing, (c) neither].

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True or False  If \(y=\log _{a}x\), then \(y=a^{x}.\)

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True or False  The graph of \(f( x) =\log _{a}x\), \(a>0\) and \(a\neq 1\), has an \(x\)-intercept equal to \(1\) and no \(y\) -intercept.

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True or False  \(\ln e^{x}=x\) for all real numbers.

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\(\ln e\)= _____.

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Explain what the number \(e\) is.

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What is the \(x\)-intercept of the function \(h( x) =\ln ( x+1) ?\)

Practice Problems

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Suppose that \(g( x) =4^{x}+2\).

  1. What is \(g( -1) \)? What is the corresponding point on the graph of \(g\)?
  2. If \(g( x) =66\), what is \(x\)? What is the corresponding point on the graph of \(g\)?

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Suppose that \(g( x) =5^{x}-3\).

  1. What is \(g ( -1) \)? What is the corresponding point on the graph of \(g\)?
  2. If \(g( x) =122\), what is \(x\)? What is the corresponding point on the graph of \(g\)?

In Problems 19–24, the graph of an exponential function is given. Match each graph to one of the following functions:

  1. \(y=3^{-x}\)
  2. \(y=-3^{x}\)
  3. \(y=-3^{-x}\)
  4. \(y=3^{x}-1\)
  5. \(y=3^{x-1}\)
  6. \(y=1-3^{x}\)

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In Problems 25–30, use transformations to graph each function. Find the domain and range.

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\(f( x) =2^{x+2}\)

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\(f( x) =1-2^{-x/3}\)

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\(f( x) =4\left( \dfrac{1}{3}\!\right) ^{\!\!\!x} \)

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\(f( x) =\left( \dfrac{1}{2}\!\right) ^{\!\!\!-x}+1\)

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\(f( x) =e^{-x}\)

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\(f( x) =5-e^{x}\)

49

In Problems 31–34, find the domain of each function.

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\(F( x) =\log _{2}x^{2}\)

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\(g( x) =8+5\ln ( 2x+3)\)

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\(f( x) =\ln ( x-1)\)

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\(g( x) = \sqrt{\ln x}\)

In Problems 35–40, the graph of a logarithmic function is given. Match each graph to one of the following functions:

  1. \(y=\log _{3}x\)
  2. \(y=\log _{3}( -x)\)
  3. \(y=-\log_{3}x \)
  4. \(y=\log _{3}x-1\)
  5. \(y=\log _{3}( x-1)\)
  6. \(y=1-\log _{3}x\)

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In Problems 41–44, use the given function f to:

  1. Find the domain of f.
  2. Graph f.
  3. From the graph of f, determine the range of f.
  4. Find \(f^{-1}\), the inverse of f.
  5. Use \(f^{-1}\) to find the range of f.
  6. Graph \(f^{-1}\).

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\(f( x) =\ln ( x+4)\)

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\(f( x) =\dfrac{1}{2}\log ( 2x)\)

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\(f( x) =3e^{x}+2\)

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\(f( x) =2^{x/3}+4\)

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How does the transformation \(y=\ln ( x+c) \), \(c>0\), affect the \(x\)-intercept of the graph of the function \(f( x) =\ln x?\)

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How does the transformation \(y=e^{cx}\), \(c>0\), affect the \(y\)-intercept of the graph of the function \(f( x) =e^{x}?\)

In Problems 47–62, solve each equation.

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\(3^{x^{2}}=9^{x}\)

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\(5^{x^{2}+8}=125^{2x}\)

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\(e^{3x}=\dfrac{e^{2}}{e^{x}}\)

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\(e^{4x}\cdot e^{x^{2}}=e^{12}\)

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\(e^{1-2x}=4\)

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\(e^{1-x}=5\)

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\(5(2^{3x}) =9\)

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\(0.3(4^{0.2x}) =0.2\)

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\(3^{1-2x}=4^{x}\)

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\(2^{x+1}=5^{1-2x}\)

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\(\log _{2}(2x+1) =3\)

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\(\log _{3}( 3x-2) =2\)

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\(\log _{x}\left( \dfrac{1}{8}\!\right) =3\)

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\(\log _{x}64=-3\)

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\(\ln ( 2x+3) =2\ln 3\)

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\(\dfrac{1}{2}\log_{3}x=2\log _{3}2\)

In Problems 63–66, use graphing technology to solve each equation. Express your answer rounded to three decimal places.

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\(\log _{5}( x+1) -\log _{4}( x-2) =1\)

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\(\ln x=x\)

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\(e^{x}+\ln x=4\)

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\(e^{x}=x^{2}\)

Question

  1. If \(f( x) =\ln ( x+4) \) and \(g( x) =\ln ( 3x+1) \), graph \( f \) and \(g\) on the same set of axes.
  2. Find the point(s) of intersection of the graphs of \(f\) and \(g\) by solving \(f( x) =g( x)\) . Label any intersection points on the graph drawn in (a).
  3. Based on the graph, solve \(f( x) > g( x).\)

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  1. If \(f( x) =3^{x+1}\) and \(g( x) =2^{x+2}\), graph \(f\) and \(g\) on the same set of axes.
  2. Find the point(s) of intersection of the graphs of \(f\) and \(g\) by solving \(f( x) =g( x) .\) Round answers to three decimal places. Label any intersection points on the graph drawn in (a).
  3. Based on the graph, solve \(f( x) >g( x).\)