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Math Help - Need Help: (X / 4) ^ 2 * 100 = Y, X = ?

  1. #1
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    Need Help: (X / 4) ^ 2 * 100 = Y, X = ?

    Hi,

    I have following formula:

    (X / 4) ^ 2 * 100 = Y

    I would like to find out the value of X, given I have the value of Y:

    X = ?

    I do not know to to move the power of 2 to the other side...

    Really appreciate your help.

    Thanks
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    Re: Need Help: (X / 4) ^ 2 * 100 = Y, X = ?

    Quote Originally Posted by michaelkamms View Post
    Hi,

    I have following formula:

    (X / 4) ^ 2 * 100 = Y

    I would like to find out the value of X, given I have the value of Y:

    X = ?

    I do not know to to move the power of 2 to the other side...

    Really appreciate your help.

    Thanks
    To undo a square you have to take a square root.
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    Re: Need Help: (X / 4) ^ 2 * 100 = Y, X = ?

    OK, got it, I think should be something like:

    (Y / 100)^(1/2) * 4

    Thanks for your help!!!
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    Re: Need Help: (X / 4) ^ 2 * 100 = Y, X = ?

    Quote Originally Posted by michaelkamms View Post
    OK, got it, I think should be something like:

    (Y / 100)^(1/2) * 4

    Thanks for your help!!!
    It's actually \displaystyle \begin{align*} \pm 4\sqrt{\frac{y}{100}} \end{align*}.
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  5. #5
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    Re: Need Help: (X / 4) ^ 2 * 100 = Y, X = ?

    Quote Originally Posted by michaelkamms View Post
    Hi,

    I have following formula:

    (X / 4) ^ 2 * 100 = Y

    I would like to find out the value of X, given I have the value of Y:

    X = ?

    I do not know to to move the power of 2 to the other side...

    Really appreciate your help.

    Thanks
    I think it will be done like this:
    (X / 4) ^ 2 = Y/100
    X / 4= √(Y/100)
    X = 4*√(Y/100)

    algebra solver
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    Re: Need Help: (X / 4) ^ 2 * 100 = Y, X = ?

    Quote Originally Posted by cobooboc View Post
    I think X=4/√(Y/100) ...
    I don't think so , read it properly. it's a minor mistake.
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  7. #7
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    Re: Need Help: (X / 4) ^ 2 * 100 = Y, X = ?

    Quote Originally Posted by michaelkamms View Post
    (X / 4) ^ 2 * 100 = Y
    I would like to find out the value of X, given I have the value of Y:
    X = ?
    C'mon guys...keep it simple

    (X / 4) ^ 2 = X^2 / 16
    SO:
    100X^2 / 16 = Y
    X^2 = 16Y / 100
    X^2 = 4Y / 25
    X = +-2SQRT(Y) / 5
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  8. #8
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    Re: Need Help: (X / 4) ^ 2 * 100 = Y, X = ?

    Indeed. Don't forget that if x^2=a, then x=\pm\sqrt{a}, not simply \sqrt{a}.
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  9. #9
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    Re: Need Help: (X / 4) ^ 2 * 100 = Y, X = ?

    (x+y)^4 - 100(x+y)^2

    (x+y) ((x+y) -100)
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    Re: Need Help: (X / 4) ^ 2 * 100 = Y, X = ?

    Quote Originally Posted by kalwin View Post
    (x+y)^4 - 100(x+y)^2

    (x+y) ((x+y) -100)
    Assuming you are trying to factorise this, you are on the right track. Now make use of the Difference Of Two Squares rule: \displaystyle \begin{align*} a^2 - b^2 = (a - b)(a + b) \end{align*}.
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