Table of contents
- 0. Review of Algebra4h 16m
- 1. Equations & Inequalities3h 18m
- 2. Graphs of Equations43m
- 3. Functions2h 17m
- 4. Polynomial Functions1h 44m
- 5. Rational Functions1h 23m
- 6. Exponential & Logarithmic Functions2h 28m
- 7. Systems of Equations & Matrices4h 6m
- 8. Conic Sections2h 23m
- 9. Sequences, Series, & Induction1h 19m
- 10. Combinatorics & Probability1h 45m
5. Rational Functions
Graphing Rational Functions
Problem 57b
Textbook Question
In Exercises 57–80, follow the seven steps to graph each rational function. f(x)=4x/(x−2)
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1
Identify the domain of the function. The function \( f(x) = \frac{4x}{x-2} \) is undefined where the denominator is zero. Set \( x-2 = 0 \) and solve for \( x \) to find the values that are not in the domain.
Determine the vertical asymptotes. Vertical asymptotes occur where the function is undefined and the numerator is not zero. From the previous step, we know \( x = 2 \) is a vertical asymptote.
Find the horizontal asymptote. For rational functions where the degree of the numerator and the denominator are the same, the horizontal asymptote is \( y = \frac{a}{b} \), where \( a \) and \( b \) are the leading coefficients. Here, the horizontal asymptote is \( y = \frac{4}{1} = 4 \).
Check for any intercepts. To find the y-intercept, set \( x = 0 \) and solve for \( f(x) \). To find the x-intercept, set \( f(x) = 0 \) and solve for \( x \).
Sketch the graph using the information from the previous steps. Plot the intercepts, draw the asymptotes as dashed lines, and sketch the curve approaching the asymptotes.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Rational Functions
A rational function is a function that can be expressed as the ratio of two polynomials. In the case of f(x) = 4x/(x−2), the numerator is 4x and the denominator is (x−2). Understanding the behavior of rational functions, including their asymptotes and intercepts, is crucial for graphing them accurately.
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Asymptotes
Asymptotes are lines that a graph approaches but never touches. For rational functions, vertical asymptotes occur where the denominator is zero, while horizontal asymptotes describe the end behavior of the function as x approaches infinity. Identifying these asymptotes helps in sketching the overall shape of the graph.
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Graphing Steps
The seven steps to graph a rational function typically include identifying the domain, finding intercepts, determining asymptotes, analyzing end behavior, and plotting points. Following these steps systematically allows for a comprehensive understanding of the function's behavior and aids in creating an accurate graph.
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