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Differential and Integral Equation




                    Notes          or
                                                                    x
                                                                     d  h  ( )
                                                                          u
                                                              x
                                                                  x
                                                                g
                                    g 1 ( )g 2 ( ) h 1 ( )h 2 ( ) Z ( ) h  1 ( ) ( )  2  Z ( )du =  f ( )g 2 ( ).
                                           x
                                                x
                                                    x
                                       x
                                                        x
                                                                                         x
                                                                               u
                                                                                             x
                                                                 2
                                                                           u
                                                                     dx g  ( )
                                                                    0    2
                                   Simplifying equation (6) we have
                                                 x                                           f ( )g  ( )
                                                                                                   x
                                                                                               x
                                                              x
                                                                           u
                                                       h 1 ( )g 2 ( )  d  h  ( )                 2
                                                         x
                                           Z ( )                         2   Z ( )du =                     ...(7)
                                                                               u
                                             x
                                                                                                        x
                                                                                          x
                                                                                                    x
                                                                                              x
                                                     x
                                                                           u
                                                              x
                                                                  x
                                                         x
                                                  g  ( )g  ( ) h  ( )h  ( ) du g  ( )   g 1 ( )g 2 ( ) h  1 ( )h  2 ( )
                                                 0  1  2     1   2       2
                                   So equation (7) is Volterra equation of the second kind. Putting
                                                                               x
                                                                           x
                                                                         h  ( )g  ( )  d  h  ( )
                                                                                            u
                                                         K  N ( , ) =     1   2            2
                                                            x
                                                             u
                                                                   [ ( )g 2 ( ) h 1 ( )h 2 ( )] du g 2 ( )
                                                                                            u
                                                                                    a
                                                                                x
                                                                           x
                                                                    g
                                                                      x
                                                                     1
                                                                               x
                                                                           x
                                                                         f ( )g  ( )
                                   and                     f  N  ( ) =        2
                                                             x
                                                                                x
                                                                    g  ( )g  ( ) h  ( )h  ( )
                                                                           x
                                                                      x
                                                                                    x
                                                                     1   2     1   2
                                   equation (7) can be put into the form
                                                  x
                                                                      x
                                            Z ( )  K N ( , ) ( )du =  f  N  ( )                            ...(8)
                                              x
                                                      x
                                                           u
                                                       u
                                                         Z
                                                  0
                                                       x
                                                  x
                                                           x
                                   Knowing  g 1 ( ), g 2 ( ), ( ),h 2 ( ) and f(x) we can then solve equation (8) by the methods of the
                                                    h
                                             x
                                                     1
                                   last unit.
                                   Self Assessment
                                   1.  Solve the integral equation
                                                   x
                                               x
                                         x
                                        y ( )  f  ( )  e  2(x u )  y ( )du
                                                           u
                                                   0
                                   26.3 Summary
                                      Volterra integral equation of  the first kind may  have a  number of  different kinds  of
                                       Kernels.
                                      It is sometimes useful to convert Volterra integral equation into Volterra integral equation
                                       of the second kind.
                                      By converting Volterra integral equation into that of second order the method of solving
                                       the Volterra integral equation of second kind may be employed.
                                   26.4 Keyword
                                   Volterra integral equation of the first kind is related to Volterra integral equation of the second
                                   kind and the solution of Volterra integral equation of the first kind can be found by the methods
                                   already used.
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