Symbol for "take the positive solution of this formula"

Question

I got a formula:

x=√(((−2*aks)/(r*(s-k)*v)))

Notice it is all wrapped inside a square root.

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When taking the square root, there are to possible outcomes as we all know. How do I denote that one should use the positive number?

Answer 1

That one. $\sqrt{a}$ denotes the positive solution of the equation $x^2 = a$.

Answer 2

Your formula does not require any change. By definition, $x = \sqrt{a}$ will return only the non-negative square root, or the principal square root. You’re confusing this with $x^2 = a \iff \vert x\vert = \sqrt{a}$, which has two solutions: $x = \pm \sqrt{a}$.

Therefore, $x = \sqrt{a}$ already implies that the returned value isn’t negative. (Note that there is no $\pm$ sign in front of the square root.)