This is a pre-calculus review to help me get ready for ap calc. I could not simplify the expression so I entered it into wolfram mathematica. I don't understand its second step though. If you could explain wolfram's steps or explain an easier method that would be great.

Here is the expression entered on wolfram: http://www.wolframalpha.com/input/?i=simplify+(9-(x^-2))/(3%2B(x^-1))