Thread: 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.

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.

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

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.

Originally Posted by cupcake

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

Originally Posted by CaptainBlack

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