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Math Help - Multiplication, quadratic equation

  1. #1
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    Unhappy Multiplication, quadratic equation

    Hi,

    I'm having trouble solving this equation.. I know it is supposed to turn out a quadratic equation, but I just can't do the math.. Would be incredibly grateful if anyone could help!!

    Here it goes:

    0,6 = √(Wa*0,4390)^2 + (Wb*0,8235)^2 + 2*(Wa*0,4390)*(Wb*0,8235)*0,253454

    Now the squareroot is supposed to cover the entire right side of the equation. Wa and Wb are unknowns.
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  2. #2
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    Are you looking to solve for them numerically or in terms of each other? As far as I know if you only have one equation and yet two unkowns you cannot solve for them numerically. Someone could correct me though.
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  3. #3
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    Thank you for answering!
    Anyway, numerically.. Sorry, I forgot to replace Wb with 1-Wa.. What I'm trying to do here is find unknown weights in a portfolio of two assets. Since Wa + Wb = 1, Wb = 1-Wa.
    For simplicity, I replaced Wa with X.

    Here is the new equation:

    0,6 = √(X*0,4390)^2+((1-X)*0,8235)^2+2*(X*0,4390)*((1-X)*0,8235)*0,253454
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  4. #4
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    Oh ok, I'd square both sides, expand all of your brackets, collect like terms. Bring all terms to one side, so the other side is zero and then apply the quadratic formula.
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  5. #5
    Grand Panjandrum
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    Quote Originally Posted by cupcake View Post
    Thank you for answering!
    Anyway, numerically.. Sorry, I forgot to replace Wb with 1-Wa.. What I'm trying to do here is find unknown weights in a portfolio of two assets. Since Wa + Wb = 1, Wb = 1-Wa.
    For simplicity, I replaced Wa with X.

    Here is the new equation:

    0,6 = √(X*0,4390)^2+((1-X)*0,8235)^2+2*(X*0,4390)*((1-X)*0,8235)*0,253454
    Try replacing:

    √(X*0,4390)^2

    by

    X*0,4390

    and then simplifying

    CB
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  6. #6
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    Quote Originally Posted by CaptainBlack View Post
    Try replacing:

    √(X*0,4390)^2

    by

    X*0,4390

    and then simplifying

    CB
    But I think he said in his original post that the square root covers the entire RHS
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