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Homework Help: Y = -3 f(x+2) - 7 (Function help!)

  1. Dec 5, 2004 #1
    Hey I am left with this question and I have no clue how to do it

    y = -3 f(x+2) - 7 (Function help!)

    1. f(x) = x
    2. f(x) = x^2
    3. f(x) = |x|
    4. f(x) = 1/x
    5. f(x) = (square root of 2) how do i write that out?

    Basically I am suppose to substitute the 5 things into the equation and the graph it. I am confident that I can graph it with no problems. However, I cant do the first part, which is to put the 5 f(x) things into the equation

    Help plz, its due tomorrow:(
    I'll check for replies frequently so if u can help me..GREAT!

    Thx in advance guys
  2. jcsd
  3. Dec 5, 2004 #2


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    Staff Emeritus
    Science Advisor
    Gold Member

    No problem! :smile:

    If you're unsure about function notation, all you need to know is this: the definition of the function tells you what to do to (how to "transform" or change) the argument (ie the variable) that you are passing into the function. So let's take an example:

    If you have a function defined by:

    f(x) = x2

    then, when you pass the argument 'x' into the function, whatever value it has is squared. Now, what if we evaluate the function for a more complicated argument?

    If f(x) = x2, then what is:

    f(x+2) ???

    Same rule! The function definition is a general statement that whatever argument is passed into the function is squared, not matter what it is.

    So f(x+2) = (x+2)2

    If you still can't see it, notice that we're just evaluating the function for a different variable, which we could define by u = x + 2. Obviously by definition:

    f(u) = u2 = (x+2)2

    Well, that example just happens to take care of your # 2. Can you do the rest?
  4. Dec 5, 2004 #3
    yes thx so much I think I understand all 5 now

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