At a Glance - Manipulating Limits
Why can't limits all get along? Ignoring them is not the answer. Sometimes we need to show them who's boss by separating them, calming them down, and then bringing them back together again.
There are some nice properties of limits that allow us to evaluate limits by breaking the limits into simpler pieces.
Throughout all of these properties, a is any real number. It can be positive, negative, zero, rational, irrational, whatever, but a must be a real number.