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Math Help - function f and g

  1. #1
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    Post function f and g

    suppose the function f and g are difined by
    f(x) = x^2 + x -2 and g (x) = 1/x

    which of the following is/are true?
    A. g ( x^2 +3 ) = 1/x^2 + 3
    B. f ( 1/x ) = 1/x^2 +x -2
    C. (f/g) (x) = x^3 + x^2 -2x and D(f/g) = R
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by Alexander View Post
    suppose the function f and g are difined by
    f(x) = x^2 + x -2 and g (x) = 1/x

    which of the following is/are true?
    A. g ( x^2 +3 ) = 1/x^2 + 3
    B. f ( 1/x ) = 1/x^2 +x -2
    C. (f/g) (x) = x^3 + x^2 -2x and D(f/g) = R
    should A. be g(x^2 + 3) = 1/(x^2 + 3)?

    and what does R mean?

    Do you know how to form composite functions? For instance, do you actually know how to find g(x^2 + 3) ? If so, simply find all the composite functions your self, and see whether they are true or not
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  3. #3
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    Quote Originally Posted by Jhevon View Post
    and what does R mean?
    I believe he means \mathbb{R}.

    And if you prefer the old German style, \mathfrak{R}.
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  4. #4
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by ThePerfectHacker View Post
    I believe he means \mathbb{R}.

    And if you prefer the old German style, \mathfrak{R}.
    yea. i realize that now. the problem was i was thinking D meant derivative (as it does when programming in maple), so i found it weird when it said D(f/g) = R. but now i realize it is talking about the domain, which makes sense, since there's no way questions of this nature would be asked in a calculus class--unless it's precalculus, in which case, derivatives still wouldn't come up
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