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Homework Help: Evaluating Functions

  1. Sep 15, 2011 #1
    1. The problem statement, all variables and given/known data

    [PLAIN]http://img89.imageshack.us/img89/6410/c3602011091514253311.jpg [Broken]

    2. Relevant equations

    Both a and b.

    3. The attempt at a solution

    For problem a, I don't know what to after that. If you could direct/tell me what to do next, I'd be able to figure it out.
    For problem b, I don't know how to set it up.
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Sep 15, 2011 #2


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    For a. , try getting rid of some denominators, it comes out very nicely.
    For b. Do exactly what you did for a. Only now because you have the function F() in the expression multiple times, so you'll have to do the substitution multiple times.

    Hope this helps enough.. but not too much.
  4. Sep 15, 2011 #3
    For a, do I multiply everything on the bottom by y?
  5. Sep 15, 2011 #4


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    Science Advisor

    Yes, multiply both numerator and denominator by y.
  6. Sep 15, 2011 #5
    This is my answer that I got.

    [PLAIN]http://img838.imageshack.us/img838/1974/c36020110915181646.jpg [Broken]

    Is it right?

    I did that but I don't know if I did it correctly.

    [PLAIN]http://img269.imageshack.us/img269/8973/c360201109151748431.jpg [Broken]
    Last edited by a moderator: May 5, 2017
  7. Sep 16, 2011 #6


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    I re-wrote the denominator like this:

    3y+4/y - 3/1

    From here I just cross multiplied:

    3y + 4 - 3y

    Combine like terms and you end up with 4/4.

    F(3y+4/y) = 1
  8. Sep 16, 2011 #7


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    Your answer to a. is correct ninjamonke, now for b. !
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