can anyone help me on how can i identify any differential equationwhether or not it is a first order differential equation? whatsignifies an equation as first order, second order,and thirdorder etc..?? Solution The highest derivative determines the order of the ODE y\' - y =4 y\' is the first derivative => first order y\'\' + y\' + 5y =5x y\'\' is thesecond derivative => second order y\'\'\' + y\' =5 y\'\'\' is the third derivative => third order.