Composition of equilibrium mixture

[Marni Kahn 1A]

When finding the composition of an equilibrium mixture, what do you do if the equation becomes a cubic instead of a quadratic?

[Benjamin Feng 1B]

Usually when you are dealing with a cubic, the Kc constant is incredibly small (<10^-4) and we can assume the dissociation is negligible. Then, when writing the Kc, you can replace any term such as .4-x or .02-2x as just .4 or .02. This simplifies the equation into usually a much easier equation to solve.

[Ally Huang- 1F]

I believe Dr. Lavelle said we would never have to solve cubic equations in this class. So, if you ever end up with a cubic equation, you should just use the initial concentrations given because the change in concentration is so small and negligible.