1. The problem statement, all variables and given/known data In the following problem they are taking the third derivative, then multiplying a 3 by 3 matrix. I don't understand how they progress from the first to the second to the third deriviative in the following two questions. These are the parts of the solution that I really don't understand What's going on? -3 sin t is not the derivative of -3 sin t The derivative of e^t(cos t - sin t) is (e^t)(-sin t - cos t) not 2e^t sin t The derivative of e^t(sin t + cos t) is (e^t)(cos t - sin t) not (2e^t)(cos t) I don't understand.