Hello all,

Here is a pretty simple equation that I need to find the critical points for. I know how to find the critical points for an equation, but I'm not able to figure this one out.

https://webwork.math.ohio-state.edu/...30dd857871.png

=>

0 = https://webwork.math.ohio-state.edu/...1a57dbec01.png

I got -21 and 0 for my critical values. Are there any more?