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Math Help - Inversely/Directly proportional SAT problem

  1. #1
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    Inversely/Directly proportional SAT problem

    If x cannot equal zero and x is inversely proportional to y, which of the following is directly proportional to 1/x^2?

    A: -1/y^2
    B: 1/y^2
    C: 1/y
    D: y
    E: y^2

    I can't seem to get my head around this problem, usually I'm pretty good at these but I just can't put this one together. I would appreciate any help, thanks.
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  2. #2
    RRH
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    Quote Originally Posted by bk brains View Post
    If x cannot equal zero and x is inversely proportional to y, which of the following is directly proportional to 1/x^2?

    A: -1/y^2
    B: 1/y^2
    C: 1/y
    D: y
    E: y^2

    I can't seem to get my head around this problem, usually I'm pretty good at these but I just can't put this one together. I would appreciate any help, thanks.
    <br />
x=\frac{1}{y}<br />

    Therefore, the problem should now look like this

    <br />
\frac{1}{(\frac{1}{y})^2}<br />

    Which is the same as

    <br />
\frac{1}{\frac{1^2}{y^2}}<br />

    Which is the same as

    <br />
\frac{1}{1} Divided by  \frac{1}{y^2}<br />

    Which is the same as

    <br />
\frac{1}{1} multiplied by \frac{y^2}{1}

    Therefore, the solution is

    <br />
y^2

    I reversed a step while typing; therefore, I have corrected my answer sorry for the confusion
    Last edited by RRH; November 14th 2009 at 12:37 PM.
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