I am writing a paper about eigenvalues and eigenvectors. I am trying to graph systems such as : x'1=x1+2x2 , x'2= 2x1+1x2 in Mathematica 9. I am looking at behaviors of linear systems and how it is determined by eigenvalues, I am directing that to Biology through population models, but I need to get some examples graphed, and I haven't had any luck. Any suggestions. Thanks, Casey