I didn't ace it, but knew immediately what I had done wrong as I rode my bicycle home. I kept checking my linear transformation matrix and the Eigen values didn't compute... Looked again at the TI-89 when I got home and realized I swapped the orientation on the Jordan constants. I wrote all the equations out, so maybe my professor will have mercy on me. Oh well, another case of elevator wit - https://en.wikipedia.org/wiki/L%27esprit_de_l%27escalier