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Basic Mathematics – I




                    Notes          2.  If a function is continuous then the constant multiple of that function is also continuous.
                                                                     Figure 8.1


















                                       Consider the  function f(x) =   . We know  that x is a constant function.  Let ‘a’  be  an

                                       arbitrary real number.
                                                         =


                                                         =


                                                         =                                                 …(i)


                                             Also    f(a)  =                                               …(ii)

                                       From (i) and (ii),
                                                          =  f(a)


                                       f(x) =    is continuous at x = a.


                                       As   is constant, and x is continuous function at x = a,    is also a continuous function at

                                       x = a.
                                                                                           2
                                   3.  Consider the function f(x) = x  + 2x. We know that the function x  and 2x are continuous.
                                                               2
                                       Now               =
                                                         =


                                                         =

                                                             2
                                                         =  a  + 2a                                        …(i)
                                                             2
                                       Also          f(a)  =  a  + 2a                                      … (ii)
                                       From (i) and (ii),    f(a)


                                       f(x) is continuous at x = a.



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