Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

If f(x+y) + f(x-y) =2f(x)f(y) and f(0)=k then find f(x)?

  1. May 30, 2008 #1
    f(x+y) + f(x-y) =2f(x)f(y)
    and f(0)=k
    then find f(x)?

    What should be approach followed to solve this question .
    plz ans it soon :blushing:
  2. jcsd
  3. May 30, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    You have an expression with f(x) and f(y) and you only want f(x). So you have to get rid of y.

    One more hint: that identity holds for all values of y.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook