Skip to main content
Logo image

Precalculus JumpStart

Worksheet 1.4 Exponential and Logarithms Pretest

Attempt the problems below to self-assess topics that need attention. Use paper and pen or pencil and number each item so you may compare with the answers later. Do NOT use a calculator, graphing tool, or AI to assist you, unless otherwise indicated. Many of the topics may be reviewed in ChapterΒ 8 below. Return to this pretest after you feel you have made sufficient progress. Answers may be found at the end of this chapter.

1. Exponential and Logarithmic Functions.

Sketch the graph of the base \(e\) exponential function, \(f(x) = e^x\text{,}\) and label at least three points on the graph including the \(y\)-intercept. State the domain and range of the graph and identify the equation of the horizontal asymptote. Then plot its inverse function’s graph \(f^{-1}(x)=\ln(x)\) on the same coordinate system. Label the corresponding points on the new curve, state its domain and range, and identify the equation of the vertical asymptote.

2. Transforming Graphs of Exponential Functions.

Discuss how the graph of \(y = 3\cdot 2^{-x} +4\) might be obtained from the graph of \(y=2^x\text{.}\) Then sketch the graph and label any relevant features. What’s the domain and range of the transformed graph?

3. Working with Logarithmic Expressions.

Evaluate each logarithmic expression, if defined. Justify your result by checking with the equivalent exponential form.
  1. \(\displaystyle \log_2 (4)\)
  2. \(\displaystyle \log_4 (2)\)
  3. \(\displaystyle \log_2 (0)\)
  4. \(\displaystyle \log_{1/2} (8)\)
  5. \(\displaystyle \ln \left(\frac{1}{\sqrt[3]{e}}\right)\)
  6. \(\displaystyle \ln(1)\)

4. Using Properties of Logarithms 1.

Given that \(\log_b(X) = 3\text{,}\) \(\log_b(Y) = -2\text{,}\) and \(\log_b(Z) = 4\text{,}\) find the exact value of
\begin{equation*} \log_b\left(\frac{X Y^2}{b^3 \, \sqrt{Z}}\right). \end{equation*}

5. Using Properties of Logarithms 2.

Express as single logarithm:
\begin{equation*} 3\ln(x) - 2 \ln(y) - \frac{1}{3} \ln(z). \end{equation*}

8. Exponential Models.

The temperature of my coffee cup after \(t\) minutes is given by \(T(t) = 140 e^{-0.2t}+60\) degrees F. Use a calculator to estimate where necessary.
  1. What’s the initial temperature of my coffee?
  2. When will my coffee be 100 degrees F?
  3. What is the temperature of the room that I am enjoying my initially hot cup of coffee?