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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
All textbooksLial 13th EditionCh. 3 - Polynomial and Rational FunctionsProblem 45
Chapter 4, Problem 45

Give the equations of any vertical, horizontal, or oblique asymptotes for the graph of each rational function. ƒ(x)=(x2+1)/(x2+9)

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Identify the rational function given: \(f(x) = \frac{x^2 + 1}{x^2 + 9}\).
Find vertical asymptotes by setting the denominator equal to zero and solving for \(x\): solve \(x^2 + 9 = 0\).
Determine if there are any real solutions to \(x^2 + 9 = 0\). If there are no real solutions, then there are no vertical asymptotes.
Find horizontal or oblique asymptotes by comparing the degrees of the numerator and denominator polynomials. Here, both numerator and denominator are degree 2.
Since the degrees are equal, the horizontal asymptote is the ratio of the leading coefficients of numerator and denominator. Write the equation of the horizontal asymptote as \(y = \frac{\text{leading coefficient of numerator}}{\text{leading coefficient of denominator}}\).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Vertical Asymptotes

Vertical asymptotes occur where the denominator of a rational function equals zero and the numerator is nonzero, causing the function to approach infinity or negative infinity. To find them, set the denominator equal to zero and solve for x. These lines indicate values that the function cannot take.
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Determining Vertical Asymptotes

Horizontal Asymptotes

Horizontal asymptotes describe the behavior of a function as x approaches positive or negative infinity. For rational functions, compare the degrees of the numerator and denominator: if degrees are equal, the asymptote is the ratio of leading coefficients; if numerator degree is less, the asymptote is y=0; if greater, no horizontal asymptote exists.
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Oblique (Slant) Asymptotes

Oblique asymptotes occur when the degree of the numerator is exactly one more than the degree of the denominator. They are found by performing polynomial long division of numerator by denominator. The quotient (without the remainder) gives the equation of the slant asymptote, representing the end behavior of the function.
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Related Practice
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