In problems below, (a) identify the independent variable and the dependent variable of each equation (use 't' for the independent variable if an independent variable is not given explicitly); (b) give the order of each differential equation (enter '1' for first order, '2' for second order and so on; do not include the quotes); and (c) state whether the equation is linear or nonlinear. If your answer to (c) is nonlinear, make sure that you can explain why this is true.

  equation  (a) independent    (a) dependent    (b) order    (c) linear/nonlinear  

You can earn partial credit on this problem.