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2.3 Polynomial and Rational Functions. Identify a Polynomial Function Identify a Rational Function Find Vertical and Horizontal Asymptotes for Rational Functions Review finding x and y intercepts of graphs.
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2.3 Polynomial and Rational Functions • Identify a Polynomial Function • Identify a Rational Function • Find Vertical and Horizontal Asymptotes for Rational Functions • Review finding x and y intercepts of graphs
Polynomial and rational functions are often used to express relationships in application problems.
Be sure to know the end behavior properties (2 and 3 below).
Go forward a few slides to see the easy-to-understand explanation.
DEFINITION: • The line x = a is a vertical asymptote if any of the following limit statements are true: • We will learn about limits in section 3.1
If c makes the denominator zero, but doesn’t make the numerator zero, then x = c is a vertical asymptote. • If c makes both the denominator and the numerator zero, then there is a hole at x=c
Example 2: Determine the vertical asymptotes of the function given by
Example 2 There are Vertical Asymptotes at x = 1 and x = -1. There isn‘t a vertical asymptote at x = 0. Since 0 makes both the numerator and denominator equal zero, there is a hole where x = 0.
Since x = 1 and x = –1 make the denominator 0, but don’t make the numerator 0, x = 1 and x = –1 are vertical asymptotes. • x=0 is not a vertical asymptote since it makes both the numerator and denominator 0.
The line y = b is a horizontal asymptote if either or both of the following limit statements are true: or We will learn about limits in section 3.1.
The graph of a rational function may or may not cross a horizontal asymptote. Horizontal asymptotes are found by comparing the degree of the numerator to the degree of the denominator. 3 cases Same: y = leading coefficient/leading coefficient BOB: y = 0 (bottom degreebigger) TUB: undefined-no H.A. (top degreebigger Bob and tub are not in the textbook.
Intercepts • The x-intercepts occur at values for which y = 0. For a fraction to = 0, the numerator must equal 0. Since 8 ≠ 0, there are no x-intercepts. • To find the y-intercept, let x = 0. y-intercept (0, 8/5)
Suppose the average cost per unitin dollars, to produce x units of a product is given by (a) find (b) How much would 10 units cost? (c) Identify any intercepts & asymptotes. Graph the function to verify your answers.
$12.50, $6.25, $3.85 • $12.50 x 10 = $125.00 • V.A. x = -30 H.A. y = 0 no x-intercepts y-intercept (0, 50/3)