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Math Help - Changing the subject of an equation

  1. #1
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    Changing the subject of an equation

    Hi guys! I am just looking for a little theory help to do with changing subjects of an equation.

    For instance
    Code:
    v = 4/3πr3
    a simple formula for working out the volume of a sphere. But I want to change the subject to r. So my question is, when you do something to both sides of an equasion, does it apply to each element of that side of the equation.

    For example changing the subject to r, my first inclination would be to multiply both sides by 3 so as to get rid of the fraction preceding Pi. (this may be wrong but its just an example.) So would i end up with
    Code:
    3v = 4πr3
    or
    Code:
    3v = 4π3r3
    ???

    Appologies for the X formating, i have not got used to the text editor on the forum yet.

    ... watch your language.
    Last edited by skeeter; May 24th 2012 at 08:38 AM.
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  2. #2
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    Re: Changing the subject of an equation

    V = \frac{4\pi r^3}{3}

    3V = 4\pi r^3

    \frac{3V}{4\pi} = r^3

    \sqrt[3]{\frac{3V}{4\pi}} = r
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