CONCEPTS AND FORMULAE:
  *  Let  ∫ f ( x )  dx  = F ( x )  +  c,  where c is the arbitrary constant of integration. The value of the integral when  x  =  b  is F ( b )  +  c and when  x  =  a, the value is F ( a )  +  c.
  *  The value of the integral when  x  =  b minus the value of the integral when   x   =   a   gives
 F ( b )  -  F ( a )  which is given as   
 Thus,    =  F (b)   -   F (a)
  *       is termed as definite integral.   ' a '  and  ' b '  are called limits of integration,
' a ' being the lower limit and  ' b ', the upper limit.
  *     is  a  definite constant unlike   which is a function of the variable ' x '.
  *   

 *      where ' c ' is some value of ' x ' between ' a ' and  ' b '.
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