Answer the following questions, and explain your reasoning. bring to class an example of a differential equation (or set of equations) describing a physiological or biological system or process. include a reference for where you got the equation (book title, author, and page number if it is from a book; title, author, journal name and volume, and publication date if it is from a journal article; or url if it is from a webpage) as well as a brief description of what the differential equation is meant to model. (make sure to include a description of what the model variables and parameters represent.) we will discuss these examples in class and decide how to classify them: linear or nonlinear? time-invariant or time-varying? causal or noncausal?