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Continuity of a function

  1. Jan 30, 2009 #1
    there is one problem. the problem is related with contuinity of afunction and i tried like as shown below.so if any one who is intersted to help me i like ..
    the problem is
    prove that if f(a+b)=f(a)f(b) for all a and b ,then f is cntiniuous at every real number.here there is given information that is the domain of f is the set of all real number and f is continuous at 0.
    I tried to approache this problem like this
    since f is continuous at 0, f(0) must defined and it must be equal to the value of limf(x) =f(0)
    and a and b are real numbers then limf(a+b)=limf(a).limf(b)
    x--->0 x-->0 x-->0
    =f(a).f(b) (since f(a) and f(b) are constnt fu.)
    this implies f is continuous at every real number.
    am i write? i want to be sure so please help
  2. jcsd
  3. Jan 30, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper

    Hi, welcome to PF.

    Try looking at
    [tex]\lim_{x \to a} f(x) = \lim_{x \to a} f( (x - a) + a )[/tex].
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