How do you graph f(x)=(x^2-1)/x using holes, vertical and horizontal asymptotes, x and y intercepts?

1 Answer
Sep 5, 2017

You have a vertical asymptote at x=0 because that would make the denominator equal zero. There's a slant asymptote at y=x because x^2/x=x

Explanation:

You know this graph can't exist at x=0, since that would make the denominator equal 0. Because the polynomial on the top is of a bigger degree, there is a slant asymptote. Dividing the initial terms, we get x^2/x=x, so there is a slant asymptote at y=x.
Since we can factor the top into (x-1)(x+1), we know the function has two solutions at x=+-1.

Plotting these solutions and following the asymptotes makes this a straightforward graph to sketch: graph{(x^2-1)/x [-10, 10, -5, 5]}

Also, not all rational functions are so easy to predict the behavior of, so creating a table of x and y values is always a good idea! And if you need more information about how to find the asymptotes, look here.