A differential equation is an equation involving differentials or differential coefficients
The solution of ordinary linear differential equations of second order with variable coefficients in the form of an infinite convergent series is called solution in series or integration in series
A transformation is a mathematical device which converts one function into another
A function f(x) which satisfies the relation f(x+T) = f(x) for all real x and some fixed T is called a periodic function.
Many physical and engineering problems when formulated in the mathematical language give rise to partial differential equations.
Semester theory examination 2012-2013