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: The ambiguous question came to my last week exam

  1. Mar 28, 2012 #1
    1. The problem statement, all variables and given/known data

    If f(x) = x^3,
    show that
    f(a,b,c) = a+b+c

    2. Relevant equations

    I have given exam last week. and i am still searching for this question .. what this is about. is it from Tensor coordinate transformation or some numerical analysis involve here.

    kindly somebody please help to solve or give idea to this question.

    3. The attempt at a solution
  2. jcsd
  3. Mar 28, 2012 #2


    Staff: Mentor

    As stated here, the question doesn't make sense. Your function f takes a single argument, so you could evaluate f(a), or f(b), or f(c), but not f(a, b, c).
  4. Mar 28, 2012 #3
    But this question came in final Exam ... It has no error as paper setter claimed ..

    How it will be solved ?
    Anybody kindly help to solve this question
  5. Mar 29, 2012 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    If this is the full problem statement as given, it has no solution because it doesn't make any sense. What is the definition of f(a,b,c) supposed to be?
  6. Mar 29, 2012 #5
    Here you go:

    Given a function f:ℝ → ℝ

    f(x) := x3

    f(a, b, c) := a + b + c

    where x, a, b, c [itex]\in[/itex] ℝ

    QED by trivialization.

    lol now it's formal
  7. Mar 30, 2012 #6
    I think all members are not taking this question seriously..

    well this question appeared in Pakistan's superior examination for recruitment in March 2012.

    this is the link of that paper..

    http://www.cssforum.com.pk/css-past-papers/css-2012-past-papers/61352-someone-please-load-app-maths-paper.html [Broken]

    it is Paper II and question No. 8(a)..

    kindly check ..
    and then put funny remarks.
    Last edited by a moderator: May 5, 2017
  8. Mar 30, 2012 #7


    User Avatar
    Science Advisor

    It's hard to be serious about non-sense. And it is still non-sense. However you define "f(x)" that gives you NO information about "f(a, b, c)". They can't be the same function.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook