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Thread: help with inverse function

  1. #1
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    help with inverse function

    here is the formula S=f(x)= 6(pi)r^2
    i believe that the inverse is r=sqrt s / 6 pi . am I correct or have I blundered.
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  2. #2
    MHF Contributor Matt Westwood's Avatar
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    Depends on where you decide to put your brackets. As it is your expression is ambiguous.
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  3. #3
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    r= (sqrt s)/ (6pi) thats what i think the answer is
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  4. #4
    MHF Contributor Matt Westwood's Avatar
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    nope

    $\displaystyle S = 6 \pi r^2$

    $\displaystyle \frac S {6 \pi} = r^2$

    $\displaystyle \sqrt {\frac S {6 \pi}} = r$
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  5. #5
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    thanks matt.

    I've got another question for the same problem f(r)=6*pi*r^2. this is what im trying to find. f^-1(f(r)).

    heres what i know from the problem already.

    f(r)= 6*pi*r^2
    f(f^-1(s))= s

    I was able to work that far but I cant mentally picture what the formula f^-1(f(r)) is. all I know is that the formulas should equal r.
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  6. #6
    MHF Contributor Matt Westwood's Avatar
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    Please post separate problems in a different thread. You might at this stage want to read the forum rules:

    http://www.mathhelpforum.com/math-he...php?do=cfrules
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