Vertical asymptote:When you have a rational expression in which the denominator is zero, you have a vertical asymptote. So to find vertical asymptotes, just set the denominator of your rational expression equal to zero, and then, solve for
![x](https://tex.z-dn.net/?f=x)
:
![\frac{x-1}{x-3}](https://tex.z-dn.net/?f=%20%5Cfrac%7Bx-1%7D%7Bx-3%7D%20)
Set the denominator equal to zero:
![x-3=0](https://tex.z-dn.net/?f=x-3%3D0)
Solve for
![x](https://tex.z-dn.net/?f=x)
:
![x=3](https://tex.z-dn.net/?f=x%3D3)
is the vertical asymptote of our rational expression.
Horizontal asymptote:Here we have two scenarios.
1) Is the degree of the denominator is higher than the degree of the numerator, you will have a horizontal asymptote at
![y=0](https://tex.z-dn.net/?f=y%3D0)
:
![y= \frac{x-1}{x^{2}+3}](https://tex.z-dn.net/?f=y%3D%20%5Cfrac%7Bx-1%7D%7Bx%5E%7B2%7D%2B3%7D%20)
Since the degree of the denominator is higher of the degree of the numerator, our rational expression will have an asymptote at
![y=0](https://tex.z-dn.net/?f=y%3D0)
2) If the degree of both denominator and numerator is the same, the rational expression will have an horizontal asymptote at the ratio of the leading coefficients:
![\frac{3x^{2}+5}{2x^2-3x+1}](https://tex.z-dn.net/?f=%20%5Cfrac%7B3x%5E%7B2%7D%2B5%7D%7B2x%5E2-3x%2B1%7D%20)
Leading coefficients: 3 and 2
Ratio of leading coefficients:
![\frac{3}{2}](https://tex.z-dn.net/?f=%20%5Cfrac%7B3%7D%7B2%7D%20)
. Our rational expression will have an horizontal asymptote at
Oblique asymptote:
If the degree of the numerator is higher than the degree of the numerator, you will have an oblique asymptote. To find it, we are going to perform long division; the quotient (without the remainder) will be the equation of the oblique asymptote line:
![\frac{x^2+5x+2}{x+1}](https://tex.z-dn.net/?f=%20%5Cfrac%7Bx%5E2%2B5x%2B2%7D%7Bx%2B1%7D%20)
The quotient of the long division is
![x-1](https://tex.z-dn.net/?f=x-1)
with a remainder of 2; therefore, the equation of the oblique asymptote line will be: