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Section 3.5 Limits at Infinity. Discuss “end behavior” of a function on an interval Graph:. As x increases without bound f(x) approaches _______. As x decreases without bound f(x) approaches _______. Definition of a Horizontal Asymptote. The line y=L is a horizontal asymptote
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Discuss “end behavior” of a function on an interval • Graph: NPR
As x increases without bound f(x) approaches _______. • As x decreases without bound f(x) approaches _______. NPR
Definition of a Horizontal Asymptote • The line y=L is a horizontal asymptote of the graph of f if Note: a function can have at most 2 horizontal asymptotes NPR
Exploration • Use a graphing utility to graph y=(2x^2 +4x-6)/(3x^2+2x-16) • Describe all important features of the graph. • Can you find a single viewing window that shows all these features clearly? • What are the horizontal asymptotes? NPR
Recall Limits at infinity: 1. If r is a positive rational number and c is any real number, then Furthermore, if x^r is defined when x<0, then 2. If the degree of the numerator is less than the degree of the denominator, then the limit of the rational function is 0. NPR
3. If the degree of the numerator is equal the degree of the denominator, then the limit of the rational function is the ratio of the leading coefficients. 4. If the degree of the numerator is greaterthan the degree of the denominator, then the limit of the rational function DNE. NPR
Examples 1) 2) 3) 4) NPR
More on Horizontal Asymptotes • Rational functions always have the same horizontal asymptote to the right and to the left. Functions that are NOT rational may approach different horizontal asymptotes. • EX: NPR
The graph: NPR
Limits involving Trig Functions 1) 2) NPR
Examples: 1) 3) 2) 4) Infinite Limits at Infinity NPR
Asymptotes • www.purplemath.com/modules/asymtote4.htm • Slant asymptotes: The graph of a rational function (having no common factors) has a slant asymptote if the degree of the numerator exceeds the degree of the denominator by 1. NPR
Find an equation for the slant asymptote: • Use long Division: NPR
References • Larson, Hostetler, and Edwards, Calculus of a Single Variable, Houghton Mifflin Company: 2002 NPR