Wednesday, July 25, 2012

Vertical Asymptotes: The Vertical Lines that never intersect the function

The vertical lines that correspond to the zeroes of the denominator of a rational function are called the Vertical Asymptotes. They occur only for those values of ‘x’ that produce zero in the denominator but not in the numerator. If  0/0 occurs, then we simply say we have a ‘hole’ in the graph. The next thing that comes to the mind is, How to find Vertical Asymptote of a given function. It involves a simple method where we just need to follow few steps to find all the values of x for which the denominator equals zero.

Following are the steps involved in finding the Vertical Asymptotes:
1. Vertical asymptote is in the form of an equation in x, x=a where f(x) is a function and f(a) does not exist.  A vertical asymptote is a vertical line which never intersects the function f(x).
2. We know that a fraction is undefined if its denominator is equal to zero. So, to find the vertical asymptote of a rational function, we need to  find the value of x such that the denominator is equal to zero.
3. In the next step, we need to equate the denominator to zero.
4. Then, we need to solve the equation in x to get the value of a.
5. Finally we need to plug in the value of a in the equation x=a, which is the vertical asymptote of the given function.

Note:  We can get more than one vertical asymptote depending on the given function

Finding Vertical Asymptote of a rational function, f(x) =(x^2+2x+3)/(x^2-5x+6). Let us first find all the x values by setting the denominator (x^2-5x+6) equal to zero and solving for ‘x’. Factorizing (x^2-5x+6) we get (x-6)(x+1)=0 and hence x = 6 and x=-1 which will make the denominator zero. Hence the vertical asymptotes of the given function are, x = 6 and x=-1.

Let us now Find Vertical and Horizontal Asymptotes of f(x)= (2x^2-5x+3)/x^2-1. The vertical asymptote is got by equating the denominator to zero, x^2-1=0. On factorization, we get (x+1)(x-1)=0. This gives us x=1 and x=-1 as the vertical asymptotes. To find the horizontal asymptote we need to first find the degree of the numerator and the denominator. Here the degree of the numerator and the denominator is the same, so, the horizontal asymptote is given by y= the coefficient of the highest degree in the numerator divided by the coefficient of the highest degree in the denominator. That gives us y=2/1=2, which is the horizontal asymptote.

Know more about the Asymptote Calculator. This article gives basic information about Asymptotes.

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