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Math Help - Simple Formula?

  1. #1
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    Simple Formula?

    Hey guys.

    I'll be honest, I haven't studied algebra in years. Last night though, I was shocked to find that I did actually want to solve an equation. I can't really rmemeber how it came about but I do remember working on it for quite a while and not getting anywhere... But it seems quite basic. Maybe you lot can help?



    What do you reckon? Is there something I can replace the question mark with?
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  2. #2
    MHF Contributor Quick's Avatar
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    Quote Originally Posted by matteus12 View Post
    Hey guys.

    I'll be honest, I haven't studied algebra in years. Last night though, I was shocked to find that I did actually want to solve an equation. I can't really rmemeber how it came about but I do remember working on it for quite a while and not getting anywhere... But it seems quite basic. Maybe you lot can help?



    What do you reckon? Is there something I can replace the question mark with?
    You have: (n/?)^2 = 2n

    find the square root of both sides: n/? = SQRT(2n)

    Multiply both sides by ? to get: n=?SQRT(2n)

    Divide both sides by the sqrt(2n) to get: n/SQRT(2n)=?

    Now we need to rationalize the denominator: (nSQRT(2n))/(2n)=?

    Which simplifies to: SQRT(2n)/2=?
    Last edited by Quick; February 18th 2007 at 05:06 AM.
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  3. #3
    Grand Panjandrum
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    Quote Originally Posted by matteus12 View Post
    Hey guys.

    I'll be honest, I haven't studied algebra in years. Last night though, I was shocked to find that I did actually want to solve an equation. I can't really rmemeber how it came about but I do remember working on it for quite a while and not getting anywhere... But it seems quite basic. Maybe you lot can help?



    What do you reckon? Is there something I can replace the question mark with?
    Let's call ? x. then what you have is:

    (n/x)^2=2n

    or:

    (n/x)(n/x)=2n

    Cancel one of the n's, and collect the x's:

    n/x^2=2,

    multiply both sides by x^2:

    n=2 x^2

    or:

    x^2=n/2

    so x= +/- sqrt(n/2)

    RonL
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  4. #4
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    I follow you right up to "so x= +/- sqrt(n/2)"?

    It's probably just the way it's written. How would I write that normally?

    Edit: Haha, never mind. I got it! It was just the way I was reading it.

    Thanks everyone.
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