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Math Help - help needed to rearrange equation

  1. #1
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    help needed to rearrange equation

    Can you please help me rearrange this equation and make z the subject:

    x = z +1/4z
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  2. #2
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    Start by adding like terms. This becomes x = 5z/4. Now divide both sides by 1.25. You have z = 4x/5

    EDIT Sorry, should have been x = 5z/4
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  3. #3
    Newbie AmberLamps's Avatar
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    Multiply both sides by 4 to get  4x = 4z + z = 5z therefore  z = 4/5x
    Last edited by AmberLamps; February 24th 2010 at 01:35 PM. Reason: woops left laptop too slow :)
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  4. #4
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    Both satx and Amber Lamps assumed that you mean x= z+ (1/4)z.

    If you meant, instead, x= z+ 1/(4z), multiply the entire equation by 4z to get 4xz= 4z^2+ 1 which is the same as 4z^2- 4xz- 1= 0.

    Solve that with the quadratic formula: z= \frac{-b\pm\sqrt{b^2- 4ac}}{2a}
    with a= 4, b= -4x and c= -1.
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  5. #5
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    Thanks everyone that has been a real help
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