AP Calculus BC : Identifying Asymptotes Graphically

Study concepts, example questions & explanations for AP Calculus BC

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Example Questions

Example Question #4 : Asymptotic And Unbounded Behavior

Asymptoteplot

\(\displaystyle \begin{align*}&\text{Decide which of the following functions, most likely represents the graph above.}\end{align*}\)

Possible Answers:

\(\displaystyle \frac{(13x + 9)}{(17x + 2)}\)

\(\displaystyle \frac{(17x + 2)}{(13x + 9)}\)

\(\displaystyle \frac{(13x - 9)}{(17x - 2)}\)

\(\displaystyle \frac{(17x - 2)}{(13x - 9)}\)

Correct answer:

\(\displaystyle \frac{(13x - 9)}{(17x - 2)}\)

Explanation:

\(\displaystyle \begin{align*}&\text{Observation of the graph shows that there’s a sharp increase}\\&\text{and decrease on either side of a particular x-value. This type}\\&\text{of behavior is observed when there’s a vertical asymptote. An}\\&\text{asymptote is a value that a function may approach, but will}\\&\text{never actually attain. In the case of vertical asymptotes, this}\\&\text{behavior occurs if the function approaches infinity for a given}\\&\text{x-value, often when a zero value appears in a denominator. Noting}\\&\text{this rule, the above function has a zero in the denominator}\\&\text{at a definite point:}\\&x=\frac{2}{17}\\&\text{We find a zero denominator for the function: }\\&\frac{(13x - 9)}{(17x - 2)}\end{align*}\)

Example Question #5 : Asymptotic And Unbounded Behavior

Asymptoteplot

\(\displaystyle \begin{align*}&\text{Which of the four following functions is depicted in the graph above?}\end{align*}\)

Possible Answers:

\(\displaystyle \frac{(4x + 18)}{(14x - 19)}\)

\(\displaystyle \frac{(4x - 18)}{(14x + 19)}\)

\(\displaystyle \frac{(14x - 19)}{(4x + 18)}\)

\(\displaystyle \frac{(14x + 19)}{(4x - 18)}\)

Correct answer:

\(\displaystyle \frac{(4x + 18)}{(14x - 19)}\)

Explanation:

\(\displaystyle \begin{align*}&\text{Observation of the graph shows that there’s a sharp increase}\\&\text{and decrease on either side of a particular x-value. This type}\\&\text{of behavior is observed when there’s a vertical asymptote. An}\\&\text{asymptote is a value that a function may approach, but will}\\&\text{never actually attain. In the case of vertical asymptotes, this}\\&\text{behavior occurs if the function approaches infinity for a given}\\&\text{x-value, often when a zero value appears in a denominator. Noting}\\&\text{this rule, the above function has a zero in the denominator}\\&\text{at a definite point centered around:}\\&x=1.3\\&\text{We find a zero denominator for the function: }\\&\frac{(4x + 18)}{(14x - 19)}\end{align*}\)

Example Question #1 : Identifying Asymptotes Graphically

Asymptoteplot

\(\displaystyle \begin{align*}&\text{Which of the four following functions is depicted in the graph above?}\end{align*}\)

Possible Answers:

\(\displaystyle \frac{(12x - 5)}{(10x + 6)}\)

\(\displaystyle -\frac{(5x + 12)}{(6x - 10)}\)

\(\displaystyle \frac{(18x + 6)}{(12x - 5)}\)

\(\displaystyle -\frac{(6x - 10)}{(5x + 12)}\)

Correct answer:

\(\displaystyle -\frac{(5x + 12)}{(6x - 10)}\)

Explanation:

\(\displaystyle \begin{align*}&\text{Notice that as x increases, the function graphed appears to}\\&\text{level out, flattening towards a certain value. This value is}\\&\text{what is known as a horizontal asymptote. An asymptote is a value}\\&\text{that a function approaches, but never actually reaches. Think}\\&\text{of a horizontal asymptote as the limit of a function as x approaches}\\&\text{infinity. In such a case, as x approaches infinity, any constants}\\&\text{added or subtracted in the numerator and denominator become}\\&\text{irrelevant. What matters is the power of x in the denominator}\\&\text{and the numerator; if those are the same, then the coefficients}\\&\text{define the asymptote. We see that the function flattens towards:}\\&f(\infty)=-0.8\\&\text{This matches the ratio of coefficients for the function: }\\&-\frac{(5x + 12)}{(6x - 10)}\end{align*}\)

Example Question #7 : Asymptotic And Unbounded Behavior

Asymptoteplot

\(\displaystyle \begin{align*}&\text{Of the following functions, which most likely represents the graph above?}\end{align*}\)

Possible Answers:

\(\displaystyle \frac{(10x - 11)}{(3x - 2)}\)

\(\displaystyle -\frac{(10x - 11)}{(3x - 2)}\)

\(\displaystyle -\frac{(3x - 2)}{(10x - 11)}\)

\(\displaystyle \frac{(3x - 2)}{(10x - 11)}\)

Correct answer:

\(\displaystyle \frac{(3x - 2)}{(10x - 11)}\)

Explanation:

\(\displaystyle \begin{align*}&\text{Notice that as x increases, the function graphed appears to}\\&\text{level out, flattening towards a certain value. This value is}\\&\text{what is known as a horizontal asymptote. An asymptote is a value}\\&\text{that a function approaches, but never actually reaches. Think}\\&\text{of a horizontal asymptote as the limit of a function as x approaches}\\&\text{infinity. In such a case, as x approaches infinity, any constants}\\&\text{added or subtracted in the numerator and denominator become}\\&\text{irrelevant. What matters is the power of x in the denominator}\\&\text{and the numerator; if those are the same, then the coefficients}\\&\text{define the asymptote. We see that the function flattens towards:}\\&f(\infty)=0.3\\&\text{This matches the ratio of coefficients for the function: }\\&\frac{(3x - 2)}{(10x - 11)}\end{align*}\)

Example Question #8 : Asymptotic And Unbounded Behavior

Asymptoteplot

\(\displaystyle \begin{align*}&\text{Of the following functions, which most likely represents the graph above?}\end{align*}\)

Possible Answers:

\(\displaystyle \frac{(17x - 5)}{(19x + 9)}\)

\(\displaystyle \frac{(19x + 9)}{(17x - 5)}\)

\(\displaystyle -\frac{(17x - 5)}{(19x + 9)}\)

\(\displaystyle -\frac{(19x + 9)}{(17x - 5)}\)

Correct answer:

\(\displaystyle -\frac{(19x + 9)}{(17x - 5)}\)

Explanation:

\(\displaystyle \begin{align*}&\text{Notice that as x increases, the function graphed appears to}\\&\text{level out, flattening towards a certain value. This value is}\\&\text{what is known as a horizontal asymptote. An asymptote is a value}\\&\text{that a function approaches, but never actually reaches. Think}\\&\text{of a horizontal asymptote as the limit of a function as x approaches}\\&\text{infinity. In such a case, as x approaches infinity, any constants}\\&\text{added or subtracted in the numerator and denominator become}\\&\text{irrelevant. What matters is the power of x in the denominator}\\&\text{and the numerator; if those are the same, then the coefficients}\\&\text{define the asymptote. We see that the function flattens towards:}\\&f(\infty)=-1.12\\&\text{This matches the ratio of coefficients for the function: }\\&-\frac{(19x + 9)}{(17x - 5)}\end{align*}\)

Example Question #9 : Asymptotic And Unbounded Behavior

Asymptoteplot

\(\displaystyle \begin{align*}&\text{Of the following functions, which most likely represents the graph above?}\end{align*}\)

Possible Answers:

\(\displaystyle -\frac{(15x - 4)}{(x + 13)}\)

\(\displaystyle -\frac{(x + 13)}{(15x - 4)}\)

\(\displaystyle -\frac{(15x + 4)}{(x - 13)}\)

\(\displaystyle -\frac{(x - 13)}{(15x + 4)}\)

Correct answer:

\(\displaystyle -\frac{(x - 13)}{(15x + 4)}\)

Explanation:

\(\displaystyle \begin{align*}&\text{Observation of the graph shows that there’s a sharp increase}\\&\text{and decrease on either side of a particular x-value. This type}\\&\text{of behavior is observed when there’s a vertical asymptote. An}\\&\text{asymptote is a value that a function may approach, but will}\\&\text{never actually attain. In the case of vertical asymptotes, this}\\&\text{behavior occurs if the function approaches infinity for a given}\\&\text{x-value, often when a zero value appears in a denominator. Noting}\\&\text{this rule, the above function has a zero in the denominator}\\&\text{at a definite point centered approximately around:}\\&x=-0.3\\&\text{We find a zero denominator for the function: }\\&-\frac{(x - 13)}{(15x + 4)}\end{align*}\)

Example Question #10 : Asymptotic And Unbounded Behavior

Asymptoteplot

\(\displaystyle \begin{align*}&\text{Of the following functions, which most likely represents the graph above?}\end{align*}\)

Possible Answers:

\(\displaystyle \frac{(9x - 11)}{(15x - 1)}\)

\(\displaystyle \frac{(9x + 11)}{(15x + 1)}\)

\(\displaystyle \frac{(15x + 1)}{(9x + 11)}\)

\(\displaystyle \frac{(15x - 1)}{(9x - 11)}\)

Correct answer:

\(\displaystyle \frac{(9x - 11)}{(15x - 1)}\)

Explanation:

\(\displaystyle \begin{align*}&\text{Observation of the graph shows that there’s a sharp increase}\\&\text{and decrease on either side of a particular x-value. This type}\\&\text{of behavior is observed when there’s a vertical asymptote. An}\\&\text{asymptote is a value that a function may approach, but will}\\&\text{never actually attain. In the case of vertical asymptotes, this}\\&\text{behavior occurs if the function approaches infinity for a given}\\&\text{x-value, often when a zero value appears in a denominator. Noting}\\&\text{this rule, the above function has a zero in the denominator}\\&\text{at a definite point centered approximately around:}\\&x=0.1\\&\text{We find a zero denominator for the function: }\\&\frac{(9x - 11)}{(15x - 1)}\end{align*}\)

Example Question #1 : Identifying Asymptotes Graphically

Asymptoteplot

\(\displaystyle \begin{align*}&\text{Decide which of the following functions, most likely represents the graph above.}\end{align*}\)

Possible Answers:

\(\displaystyle \frac{(12x - 20)}{(17x)}\)

\(\displaystyle -\frac{(17x)}{(12x - 20)}\)

\(\displaystyle -\frac{(12x - 20)}{(17x)}\)

\(\displaystyle \frac{(17x)}{(12x - 20)}\)

Correct answer:

\(\displaystyle \frac{(12x - 20)}{(17x)}\)

Explanation:

\(\displaystyle \begin{align*}&\text{Notice that as x increases, the function graphed appears to}\\&\text{level out, flattening towards a certain value. This value is}\\&\text{what is known as a horizontal asymptote. An asymptote is a value}\\&\text{that a function approaches, but never actually reaches. Think}\\&\text{of a horizontal asymptote as the limit of a function as x approaches}\\&\text{infinity. In such a case, as x approaches infinity, any constants}\\&\text{added or subtracted in the numerator and denominator become}\\&\text{irrelevant. What matters is the power of x in the denominator}\\&\text{and the numerator; if those are the same, then the coefficients}\\&\text{define the asymptote. We see that the function flattens towards:}\\&f(\infty)=0.71\\&\text{This matches the ratio of coefficients for the function: }\\&\frac{(12x - 20)}{(17x)}\end{align*}\)

Example Question #2 : Identifying Asymptotes Graphically

Asymptoteplot

\(\displaystyle \begin{align*}&\text{Decide which of the following functions, most likely represents the graph above.}\end{align*}\)

Possible Answers:

\(\displaystyle -\frac{(9x - 4)}{(16x - 13)}\)

\(\displaystyle -\frac{(16x - 13)}{(9x - 4)}\)

\(\displaystyle \frac{(16x - 13)}{(9x - 4)}\)

\(\displaystyle \frac{(9x - 4)}{(16x - 13)}\)

Correct answer:

\(\displaystyle \frac{(16x - 13)}{(9x - 4)}\)

Explanation:

\(\displaystyle \begin{align*}&\text{Notice that as x increases, the function graphed appears to}\\&\text{level out, flattening towards a certain value. This value is}\\&\text{what is known as a horizontal asymptote. An asymptote is a value}\\&\text{that a function approaches, but never actually reaches. Think}\\&\text{of a horizontal asymptote as the limit of a function as x approaches}\\&\text{infinity. In such a case, as x approaches infinity, any constants}\\&\text{added or subtracted in the numerator and denominator become}\\&\text{irrelevant. What matters is the power of x in the denominator}\\&\text{and the numerator; if those are the same, then the coefficients}\\&\text{define the asymptote. We see that the function flattens towards:}\\&f(\infty)=1.78\\&\text{This matches the ratio of coefficients for the function: }\\&\frac{(16x - 13)}{(9x - 4)}\end{align*}\)

Example Question #3 : Identifying Asymptotes Graphically

Asymptoteplot

\(\displaystyle \begin{align*}&\text{Of the following functions, which most likely represents the graph above?}\end{align*}\)

Possible Answers:

\(\displaystyle -\frac{(3x + 14)}{(15x - 16)}\)

\(\displaystyle \frac{(3x + 14)}{(15x - 16)}\)

\(\displaystyle \frac{(15x - 16)}{(3x + 14)}\)

\(\displaystyle -\frac{(15x - 16)}{(3x + 14)}\)

Correct answer:

\(\displaystyle \frac{(3x + 14)}{(15x - 16)}\)

Explanation:

\(\displaystyle \begin{align*}&\text{Notice that as x increases, the function graphed appears to}\\&\text{level out, flattening towards a certain value. This value is}\\&\text{what is known as a horizontal asymptote. An asymptote is a value}\\&\text{that a function approaches, but never actually reaches. Think}\\&\text{of a horizontal asymptote as the limit of a function as x approaches}\\&\text{infinity. In such a case, as x approaches infinity, any constants}\\&\text{added or subtracted in the numerator and denominator become}\\&\text{irrelevant. What matters is the power of x in the denominator}\\&\text{and the numerator; if those are the same, then the coefficients}\\&\text{define the asymptote. We see that the function flattens towards:}\\&f(\infty)=0.2\\&\text{This matches the ratio of coefficients for the function: }\\&\frac{(3x + 14)}{(15x - 16)}\end{align*}\)

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