The numerator x²-x-6 factors as (x-3)(x+2)

To see how to do that watch this youtube video:


http://www.youtube.com/watch?v=jR6RBA9bois&feature=relmfu

The denominator x²-4 factors as (x-2)(x+2)

To see how to do that watch this youtube video:

http://www.youtube.com/watch?v=_qyVzH3e1dY

So



becomes



Now the (x+2) on the top cancels with the (x+2)
on the bottom, like this:



And all that's left is



Edwin