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Ch. 3 - Polynomial and Rational Functions
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514Not the one you use?Change textbook
Chapter 4, Problem 75

Follow the seven steps to graph each rational function. f(x)=x4/(x2+2)

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1
Identify the domain of the function \(f(x) = \frac{x^{4}}{x^{2} + 2}\). Since the denominator is \(x^{2} + 2\), which is always positive for all real \(x\), the domain is all real numbers, \((-\infty, \infty)\).
Find the intercepts: For the y-intercept, evaluate \(f(0) = \frac{0^{4}}{0^{2} + 2}\). For the x-intercepts, set the numerator equal to zero, \(x^{4} = 0\), and solve for \(x\).
Determine the vertical asymptotes by finding values of \(x\) that make the denominator zero. Since \(x^{2} + 2 = 0\) has no real solutions, there are no vertical asymptotes.
Find the horizontal or oblique asymptotes by comparing the degrees of the numerator and denominator. The numerator degree is 4 and the denominator degree is 2. Since the numerator degree is greater, perform polynomial division of \(x^{4}\) by \(x^{2} + 2\) to find the oblique asymptote.
Analyze the end behavior of the function using the quotient from the polynomial division and sketch the graph accordingly, including the intercepts and asymptotes found.

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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 ratio of two polynomials, expressed as f(x) = P(x)/Q(x), where Q(x) ≠ 0. Understanding the domain, zeros, and behavior of both numerator and denominator is essential for graphing and analyzing these functions.
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Domain and Vertical Asymptotes

The domain of a rational function excludes values that make the denominator zero. These values often correspond to vertical asymptotes, where the function approaches infinity or negative infinity, indicating important features in the graph.
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Determining Vertical Asymptotes

End Behavior and Horizontal/Oblique Asymptotes

End behavior describes how the function behaves as x approaches infinity or negative infinity. For rational functions, this is determined by comparing the degrees of numerator and denominator, which helps identify horizontal or oblique asymptotes guiding the graph's long-term trend.
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Determining Horizontal Asymptotes