Is there any possible way that the critical points for an equation can be found out short of find when the equation = 0, or is not defined?

The equation I have is

I can't figure out how to factor it, and it's also just undefinable if it's put through the quadratic equation.

So I have no idea how I'm supposed to find the critical points. I know there has to be two turning points seeing as it's third degree, but can't figure out what I should be doing..