Equilibrium concentrations/ finding x

[Shaniya Kerns 4D]

How do you know when to square root of the expression of Kc in terms of x or when to use the quadratic equation to find x. Also when x is found which value is to be used?

[Soumya 2D]

when Kc is less than 10^-3 you don't have to use the quadratic formula.

[Landon Ta-Tran 3K]

There is also another way to determine whether you need to use the quadratic formula or not. This is when the x, or equilibrium value of the products, is less than 5% of the original concentration of reactants. This determines how much the reactant dissociates and can be used to label such substance is weak. If the dissociation is little or less than 5%, the equilibrium value of the products can be considered negligible, as it won't affect the equilibrium constant value that much.