Calc A/B critical points

[thin perch]

I have to find the critcal point, I understand how to break down the derrivative, I just don't understand the simplification after that

[hallow furnace]

1. Wait patiently for a helper to come along.
2. Once someone helps you, say thank you and close the thread with:

+close

3. Feel free to nominate the person for helper of the week in #helper-nominations
4. Do not ping the mods, unless someone is breaking the rules.
5. If you're happy with the help you got here, and the server overall, you can contribute financially as well:

[rain crescent]

I've heard about supercritical points