Evaluate and graph the following expression:

$\underset{x\to \mathrm{-3}}{lim}\left(\frac{{x}^{2}-9}{x+3}\right)$

Sometimes, simple substitution can't be used to evaluate a limit because the results of the substitution are indeterminate (e.g. dividing a number by 0). When that happens, a different technique needs to be applied.
Here we illustrate how we first use algebraic simplification to create an equation that can be evaulated by substitution.
Calculus Review - Evaluating Limits by Simplification