In Algebra today, we learned how to compare linear and non-linear graphs. To do this all you have to go is look at the graph and determne whether it is straight or not. If it is straight then it is linear. If it is curved in any way, then it is non-linear. We also had to give the domain (the x-values). The domain is negative infiniti to positive infiniti. The domain of a non-linear graph varies depending on the type of graph.