1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Function Help

  1. Apr 2, 2008 #1
    1. The problem statement, all variables and given/known data

    If f{x + p } = f{x} for all x..then p is called the period of the function.

    This part is clear to me.Now the book says...

    The period of the function f{ax + b} is b/a.Can someone lead me through.

    2. Relevant equations

  2. jcsd
  3. Apr 2, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    Hi physixguru! :smile:

    hmm :confused: … I think they must mean:
    The period of a function f for which f{ax + b} = f{x} for all x is b/a. :smile:

    EDIT: ooh … that's not right … thinks … I think they mean the same f, and it's p not b:

    The period of f{ax + b} is p/a. :smile:

    Hint: put g(x) = f(ax + b). Then … ? :smile:
    Last edited: Apr 2, 2008
  4. Apr 2, 2008 #3
    I need the xplanation.
  5. Apr 2, 2008 #4


    User Avatar
    Science Advisor
    Homework Helper

    Hi! see edit of previous post.

  6. Apr 2, 2008 #5


    User Avatar
    Science Advisor

    If f is a function with period p, that is, if f(x+ p)= f(x) for all x, then f completes one period as x goes from 0 to p. g(x)= f(ax+ b) will complete a period as ax+ b goes from 0 to p. That is, from ax+ b= 0 so x= -b/a, to ax+ b= p so x= (p- b)/a that is a "distance" of (p- b)/a- (-b/a)= p/a- b/a+ b/a. If f has period p, then f(ax+ b) has period p/a, not b/a.
  7. Apr 4, 2008 #6
    Thats right...i was cured when ya told me that it was p/a.
    thnx all.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook