In general, an equation involving  derivative (derivatives) of the dependent variable
with respect to independent variable (variables) is called a differential equation A differential equation involving derivatives of the dependent variable with respect
to only one independent variable is called an ordinary differential equation, e g ,
3
2
2 d y2
dy
dx
dx
⎛
⎞
+ ⎜
⎟
⎝
⎠
 = 0  is an ordinary differential equation