AP Calculus AB: 8.5.4 Functions with Asymptotes and Holes
This content explains how to analyze rational functions that have vertical and horizontal asymptotes, as well as holes (point discontinuities). It focuses on factoring, canceling common terms, and understanding how a removable discontinuity (hole) occurs when both the numerator and denominator share a factor that becomes undefined in the original function.
Functions with Asymptotes and Holes
Identify vertical asymptotes for a rational function by factoring the numerator and denominator, canceling where possible, and determining where the resulting denominator is zero. A vertical asymptote to the graph of a function f is a line whose equation is x = a, where
, or .
• Identify horizontal asymptotes by taking the limit of the function as x approaches positive or negative infinity. A horizontal asymptote to the graph of a function f is a line whose equation is y = a, where , or .
• A hole (or point discontinuity) occurs in the graph of a function f at a point c if not equal to exists and f(c) is undefined or .
Key Terms
Functions with Asymptotes and Holes
Identify vertical asymptotes for a rational function by factoring the numerator and denominator, canceling where possible, and determining where th...
note
When graphing a rational function, first look for
vertical asymptotes.This function can be factored. The numerator and
Which of the following curves is the graph of the equation
f(x) = x+3 / x^2+4x+3?
The correct graph is a rational function with vertical asymptotes at x=−1x = -1x=−1, a hole at x=−3x = -3x=−3, and approaches 0 as x→±∞x \to \pm\in...
Which of the following curves is the graph of the equation
f(x) = x^2−x−6 / x^2+x−2?
The correct graph has a vertical asymptote at x=1x = 1x=1, a hole at x=−2x = -2x=−2, and a horizontal asymptote at y=1y = 1y=1.
Which of the following curves is the graph of the equation
f(x) = −x^2+x+6 / x^2+x−2?
The correct graph has vertical asymptotes at x=1x = 1x=1 and x=−2x = -2x=−2, and a horizontal asymptote at y=−1y = -1y=−1.
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| Term | Definition |
|---|---|
Functions with Asymptotes and Holes | Identify vertical asymptotes for a rational function by factoring the numerator and denominator, canceling where possible, and determining where the resulting denominator is zero. A vertical asymptote to the graph of a function f is a line whose equation is x = a, where |
note |
|
Which of the following curves is the graph of the equation f(x) = x+3 / x^2+4x+3? | The correct graph is a rational function with vertical asymptotes at x=−1x = -1x=−1, a hole at x=−3x = -3x=−3, and approaches 0 as x→±∞x \to \pm\inftyx→±∞. |
Which of the following curves is the graph of the equation f(x) = x^2−x−6 / x^2+x−2? | The correct graph has a vertical asymptote at x=1x = 1x=1, a hole at x=−2x = -2x=−2, and a horizontal asymptote at y=1y = 1y=1. |
Which of the following curves is the graph of the equation f(x) = −x^2+x+6 / x^2+x−2? | The correct graph has vertical asymptotes at x=1x = 1x=1 and x=−2x = -2x=−2, and a horizontal asymptote at y=−1y = -1y=−1. |