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Differential and Integral Equation                            Sachin Kaushal, Lovely Professional University




                    Notes                 Unit 27: Volterra Integral Equations and Linear
                                                          Differential Equations


                                     CONTENTS

                                     Objectives
                                     Introduction

                                     27.1 Relation between Linear Differential Equations and Volterra Integral Equations
                                     27.2 Conversion of Volterra Integral Equation of Second Kind into a Differential Equation
                                     27.3 Summary

                                     27.4 Keywords
                                     27.5 Review Questions

                                     27.6 Further Readings
                                  Objectives


                                  After studying this unit, you should be able to:
                                      Know that the existence and uniqueness of the solution of differential equations leads us
                                       to the integral equations
                                      See the relation between the integral equations and the linear differential equations with
                                       initial conditions.

                                      Understand that the solution of the integral equation also satisfies a certain differential
                                       equation with boundary conditions.

                                  Introduction

                                  The connection between a differential equation and integral equation should be seen clearly.

                                  This connection helps us to solve certain differential equations by converting it into an integral
                                  equation and vice versa.

                                  27.1 Relation between Linear Differential Equations and Volterra

                                       Integral Equations

                                  In the unit 24 we had seen that a differential equation of first order or second order under certain
                                  conditions is converted into an integral equation. This idea can be further explained in details in
                                  this unit. Let us consider an nth order linear differential equation as follows:
                                           n
                                          d y      d n  1 y   d  n  2 y
                                                                              x
                                                            x
                                               a 1 ( )   a  2 ( )   ...... a y  f  ( )                     ...(1)
                                                 x
                                                                         n
                                          dx n     dx n  1    dx n  2
                                  It  is assumed that  the  unknown functions  y(x),  f(x),  a (x) a (x),...a (x) are  continuous  and
                                                                                 1   2     n
                                  differentiable on the interval (a, b). The function y(x) satisfies the following initial conditions:
                                                                    (n  1)  (n  1)
                                                                    y
                                          y (0)  y  , (0)  y  , y  (0)  y  ...... (0)  y  ...              ...(2)
                                                  y
                                                0       0        0         0
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