Asymptote

line that a curve approaches, as it heads towards infinity:
Asymptote

Types

There are three types: horizontal, vertical and oblique:
Asymptote Types

it can be in a negative direction,

the curve can approach from any side (such as from above or below for a horizontal asymptote),
Asymptote Crossing
or may actually cross over (possibly many times), and even move away and back again.
The important point is that:
The distance between the curve and the asymptote tends to zero as they head to infinity (or −infinity)

Horizontal Asymptotes

Horizontal Asymptote
It is a Horizontal Asymptote when:
as x goes to infinity (or −infinity) the curve approaches some constant value b

Vertical Asymptotes

Vertical Asymptote
It is a Vertical Asymptote when:
as x approaches some constant value c (from the left or right) then the curve goes towards infinity (or −infinity).

Oblique Asymptotes

Oblique Asymptote
It is an Oblique Asymptote when:
as x goes to infinity (or −infinity)then the curve goes towards a liney=mx+b
(note: m is not zero as that is a Horizontal Asymptote).

Example: (x2-3x)/(2x-2)

The graph of (x2-3x)/(2x-2) has:
  • A vertical asymptote at x=1
  • An oblique asymptote: y=x/2-1
 Asymptote Example