1. January 19, 2010
Graphing Rational Functions
Functions of the form
where a(x) and b(x) are polynomial functions.
Examples

2. January 19, 2010
Graphing Rational Functions
Appearance
Where n is even, the Where n is odd, the
graph looks like this: graph looks like this:

3. January 19, 2010
Graphing Rational Functions
Sketching (7 steps)
Step 1: Find the y-intercept (let x = 0)
Step 2: Factor everything. (Use rational roots theorem if necessary.)
Step 3: Find the roots of the function by finding the roots of the
numerator a(x).
Step 4: Find the vertical asymptotes by finding the roots of the
denominator b(x).

4. January 19, 2010
Graphing Rational Functions
Step 5: Find the horizontal asymptotes by dividing each term in the
function by the highest power of x, and take the limit as x goes to infinity.
(Use the UNfactored form.)
You will find that, in general, there are three possible results:
i When [degree of numerator < degree of denominator]
the horizontal asymptote is y = 0.
ii When [degree of numerator = degree of denominator]
the H.A. is the ratio leading coefficient of a(x)
leading coefficient of b(x)
iii When [degree of numerator > degree of denominator] there is
no horizontal asymptote; however there may be a slant asymptote or
a hole in the graph.

5. January 19, 2010
Graphing Rational Functions
Sketching (7 steps)
Step 6: Determine the sign of the function over the intervals defined by
the roots and vertical asymptotes. (Use the factored form.)
Step 7: Sketch the graph.

6. January 19, 2010
Graphing Rational Functions
Sketching: Example 1 of 4
Step 1: Step 5:
Step 6:
Step 2:
Step 3: Step 7:
Step 4:

7. January 19, 2010
Step 5:

8. January 19, 2010
Sketch the graph of

9. January 19, 2010

10. January 19, 2010

11. January 19, 2010
Graphing Rational Functions
Sketching: Example 2 of 4
Step 5:
Step 1:
Step 6:
Step 2:
Step 7:
Step 3:
Step 4:

12. January 19, 2010
Step 5: