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Ch. 3 - Polynomial and Rational Functions
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook
Chapter 4, Problem 74b

Solve each problem. Work each of the following. Find an equation for a possible corresponding rational function.

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1
Understand that a rational function is a function of the form \(f(x) = \frac{P(x)}{Q(x)}\), where \(P(x)\) and \(Q(x)\) are polynomials and \(Q(x) \neq 0\).
Identify the key features or conditions given in the problem (such as zeros, vertical asymptotes, horizontal asymptotes, or points the function must pass through) to determine the form of \(P(x)\) and \(Q(x)\).
Construct the numerator polynomial \(P(x)\) using the zeros of the function. For example, if the function has zeros at \(x = a\) and \(x = b\), then \(P(x)\) could include factors like \((x - a)\) and \((x - b)\).
Construct the denominator polynomial \(Q(x)\) using the vertical asymptotes or restrictions on the domain. For example, if there is a vertical asymptote at \(x = c\), then \(Q(x)\) could include a factor like \((x - c)\).
Combine \(P(x)\) and \(Q(x)\) to write the rational function \(f(x) = \frac{P(x)}{Q(x)}\). Adjust coefficients if necessary to satisfy any additional conditions such as specific function values.

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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 structure of rational functions helps in identifying their behavior, domain restrictions, and possible forms of the equation.
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Domain and Restrictions

The domain of a rational function excludes values that make the denominator zero, as division by zero is undefined. Identifying these restrictions is essential to correctly form the function and understand its graph.
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Constructing Rational Functions from Conditions

To find an equation for a rational function, one often uses given conditions such as zeros, vertical asymptotes, or points on the graph. These conditions guide the selection of factors in the numerator and denominator to build the function.
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Intro to Rational Functions