Asymptote
Definition

An asymptote is a line (or curve) that the graph of a relation at some point gets closer and closer to.


An asymptote is a line (or curve) such that as a point moves along the curve (never stopping), the distance from the point to the asymptote approaches zero.


Note that the curve may, or may not, intersect the asymptote, but beyond a certain point will approach the asymptote, never reaching it.

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Vertical Asymptote Examples

Given a function and the corresponding reciprocal function, the graph of the reciprocal function will have vertical asymptotes where the function has zeros (the x-intercept(s) of the graph of the function).


f(x) = ( x - 3 )2 - 4.  r(x)  is the reciprocal function of f(x).


f(x)  has zeros of  1  and  5  [x-intercepts of  ( 1, 0 ),  ( 5, 0 )].

r(x)  has two vertical asymptotes with equations  x = 1  and  x = 5.


Vertical asymptotes example

Limits examples

The graph of a function may have zero, one or many vertical asymptotes.


Limits examples

Horizontal Asymptote Example

The graph of a function may have exactly zero or one horizontal asymptote.

The graph of a function will never have more than one horizontal asymptote.


Horizontal asymptotes example

Observe from the graph that as x gets larger and larger (approaching positive infinity) that:

Observe from the graph that as x gets smaller and smaller (approaching negative infinity) that:


Other Examples of Asymptotes

Example One: A horizontal line other than the x-axis

Horizontal asymptotes example

Example Two: A slant asymptote

Horizontal asymptotes example

Example Three: A non-linear asymptote

Horizontal asymptotes example