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Rational Functions and Asymptotes. Let’s find: vertical , horizontal, and slant asymptotes when given a rational function. Get Started. MAIN MENU. All done?. Example A. Example B. You try. What is a Rational Function?. A function that is the ratio of two polynomials. A few examples…….
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Rational Functions and Asymptotes Let’s find: vertical, horizontal, and slant asymptotes when given a rational function. Get Started
MAIN MENU All done? Example A Example B You try
What is a Rational Function? A function that is the ratio of two polynomials. A few examples…… It is “Rational” because one is divided by the other, like a ratio. Return to Main Menu
What is an asymptote? A line that a curve approaches but never reaches, or “touches” Return to main menu
Vertical Asymptotes To find the vertical asymptote of a function, we must set the denominator equal to zero and solve for x. There will be a vertical asymptote, x = 2. Back to Main Menu
Horizontal Asymptotes • Compare the degrees of the numerator and denominator. We will let the denominator degree be “d” and the numerator degree be “n.” There are 3 cases Case 1 n < d Case 2 n > d Case 3 n = d
Case 1 If n < d, then y = 0 is a horizontal asymptote(HA) of the function. HA: y = 0 Return to main menu
Case 2 If n > d, then there is no horizontal asymptote (HA). HA : none Return to main menu
Case 3 If n = d, then the horizontal asymptote is the ratio of the numerator leading coefficient over the denominator leading coefficient. HA: Return to main menu
Slant Asymptote If the degree of the numerator (n) is EXACTLY one greater that the degree of the denominator (d), there will be a slant asymptote. Since the degree of the numerator is 2 and the degree of the denominator is 1, there will be a slant asymptote. Return to Main Menu Lets find the slant asymptote
Let’s find the slant asymptote We must divide the denominator into the numerator The line y = x – 2 is the slant asymptote of the rational function. Please note, if there is a remainder upon dividing, we discard it as it will have no affect on the rational function as x approaches infinity. Return to Main Menu
Example A Find all asymptotes of the function g(x). Vertical Asymptotes Set the denominator equal to zero and solve. Horizontal Asymptotes Compare degrees…. Numerator-degree of 1 Denominator-degree of 2 Since n < d, HA: y = 0 Return to Main Menu VA: x =2, x=-2
Example B Find all asymptotes of the function f(x). Vertical Asymptotes: Set the denominator equal to zero and solve Horizontal Asymptotes: Compare degrees…. Numerator-degree of 2 Denominator-degree of 2 Since n = d, HA: y = 2 Return to Main Menu VA: x = -3, x = 2
You Try Find all asymptotes for A.) VA: none, HA: y = 1 B) VA: x = -1, HA: y=0 Return to Main Menu C) VA: x = 1, x = -1, HA: y = 0
Hmmmm, better try again Back to choices Return to Main Menu
Correct ! Back to choices Return to Main Menu
All Done? Let’s Review! • To find vertical asymptotes - set the denominator equal to zero and solve. • To find horizontal asymptotes - compare the degree of the numerator to the degree of the denominator. • To find slant asymptotes - divide the numerator by the denominator. Return to Main Menu References
References Retrieved 9/22/13 Dreamstime http://www.animationlibrary.com animation/22939/Yellow_dog_thinks/ Retrieved 9/22/13 Dreamstime http/www.animationlibrary.com/animation/22938/Yellow_dog_sings/ Larson, R. (2011). Algebra and Trigonometry. Belfast, CA: Cengage Asymptotes. Retrieved from Mathisfun.com Return to Main Menu