Chapter 4: Problem 48
Sketch the graph of \(f\). $$f(x)=\log _{2} \sqrt[3]{x}$$
Short Answer
Expert verified
The graph of \(f(x)=\log_{2} \sqrt[3]{x}\) passes through \((1,0)\), has a vertical asymptote at \(x=0\), and grows slowly to infinity as \(x\) increases.
Step by step solution
01
Understand the Function
The function given is \(f(x)=\log _{2} \sqrt[3]{x}\). This means we are dealing with a logarithmic function with base 2 of the cube root of \(x\). The cube root of \(x\) can be rewritten as \(x^{1/3}\). Therefore, the function can be expressed as \(f(x) = \frac{1}{3} \log_{2}(x)\).
02
Identify Key Features
For the function \(f(x) = \frac{1}{3} \log_{2}(x)\), it is only defined for \(x > 0\). There is no output for \(x \leq 0\). The logarithmic function always passes through the point where the argument of the log function is 1, that is, \(f(1) = \frac{1}{3} \log_{2}(1) = 0\). So, the graph will pass through the point \((1, 0)\).
03
Determine the Asymptote
As \(x\) approaches 0 from the positive side, \(\log_{2}(x)\) approaches \(-\infty\). Therefore, the graph has a vertical asymptote at \(x = 0\).
04
Analyze the Behavior at Infinity
As \(x\) approaches infinity, \(f(x)\) will also go to infinity, albeit slowly. This is because \(f(x) = \frac{1}{3} \log_{2}(x)\) grows logarithmically.
05
Sketch the Graph
Start the graphing at \((1, 0)\) since \(f(1) = 0\). Draw the curve to show the behavior moving towards \(-\infty\) as \(x\) approaches 0 from the positive side. Show that the curve grows slowly to \(\infty\) as \(x\) moves to \(\infty\). Ensure there is a vertical asymptote at \(x=0\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Graphing Logarithmic Functions
Graphing a logarithmic function involves interpreting how the function behaves for different values of the variable. For the function \(f(x) = \frac{1}{3} \log_{2}(x)\), the key feature is that it only exists for \(x > 0\). You plot the logarithmic curve starting from the point where the argument of the logarithm equals 1, i.e., \((1, 0)\). This is because the logarithms of 1 is always zero.
- Logarithmic graphs are defined on the positive x-axis.
- The graph passes through the point where the logarithm's argument is 1.
- The curve slowly rises in the positive x-axis direction.
Asymptotes
An asymptote is a line that a graph approaches but never touches or crosses. In the case of the function \(f(x) = \frac{1}{3} \log_{2}(x)\), there is a vertical asymptote at \(x = 0\).
- A vertical asymptote means that as \(x\) gets closer to 0, the value of \(f(x)\) decreases towards negative infinity.
- Logarithmic functions commonly have vertical asymptotes where their argument is zero.
Cube Root
The cube root function \(\sqrt[3]{x}\) can be rewritten as \(x^{1/3}\). This transformation is helpful to better understand the behavior of the given logarithmic function. In this exercise, the expression \(\log_{2}(\sqrt[3]{x})\) simplifies to \(\frac{1}{3}\log_{2}(x)\).
- The cube root is the same as raising \(x\) to the power of \(\frac{1}{3}\).
- Knowing how to manipulate these expressions helps in simplifying logarithmic functions.
Transformations of Functions
Transformations are modifications to the function's form, which shift, stretch, or compress the graph. For \(f(x) = \frac{1}{3} \log_{2}(x)\), this transformation is a vertical compression by a factor of \(\frac{1}{3}\).
- Vertical transformations affect the graph's height.
- Multiplying the logarithmic output by \(\frac{1}{3}\) flattens the growth rate.