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Function without statement

  1. Jun 5, 2017 #1
    1. The problem statement, all variables and given/known data
    I am trying solve a question which invokes a function f(…) and the argument of function is the same function with -1 as an argument i.e.

    f(f(-1))

    However the statements of the function are not provided. Instead a graph is provided which is uploaded. I cant understand which variable of the graph i.e. x or y will get this value of -1?

    Somebody please guide me?


    2. Relevant equations
    f(f(-1))



    3. The attempt at a solution
    I cant understand what would happen when function f(-1) is invoked. What statements would be executed? Which variable of the graph would get -1?


    Somebody please guide me.
    Zulfi.
     

    Attached Files:

  2. jcsd
  3. Jun 5, 2017 #2
    Find ##f(-1)##.
     
    Last edited by a moderator: Jun 5, 2017
  4. Jun 5, 2017 #3

    SammyS

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    Staff Emeritus
    Science Advisor
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    Gold Member

    Your figure:
    function-without-statement-etsp181-jpg.jpg
    I suppose the graph is to be interpreted as being y = ƒ(x) .

    Is that how such graphs tend to be treated in your course/book ?
     
  5. Jun 5, 2017 #4

    mfb

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    2016 Award

    Staff: Mentor

    How do you simplify expressions like 5+(3*(4-1))? You start from the inside.
    To evaluate f( f(-1) ), first find f(-1).
     
  6. Jun 5, 2017 #5

    Mark44

    Staff: Mentor

    You don't need the function definition, since you have a graph of the function.

    Follow the suggestion made by @Buffu.
     
  7. Jun 6, 2017 #6
    Hi,
    Thanks.
    Based upon this rule:
    y=f(-1)
    Find the value of y for x=-1 from the graph
    therefore y=2
    Now f(f(-1)) = f(2)
    Find the value of y for x=2 from the graph
    therefore y= 1
    Therefore answer of f(f(-1)) is 1.

    This is correct.

    Zulfi.
     
  8. Jun 6, 2017 #7

    Mark44

    Staff: Mentor

    Your answer is correct, but you're writing a lot more than is necessary.
    This is how I would do it.

    From the graph, f(-1) = 2, and f(2) = 1,
    so f(f(-1)) = f(2) = 1.​
     
  9. Jun 6, 2017 #8
    Hi,
    Thanks for improving my solution. God bless you.

    Zulfi.
     
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