31 For each of the following ordinary differential equations
     3.1. For each of the following ordinary differential equations, determine its order and whether or not it is linear:  
  
  Solution
(c) is of order 3 and it is Linear.All Terms in terms of y have highest power 1.so the Differential equation is Linear
(d) It is of order 2 and it is Non -Linear as there are terms with y\'^2 which is non linear term and so the equation is a Non Linear Ordinary Differential Equation

