This question smells like it out to live on https://math.stackexchange.com/.
It might be on-topic because:
- It's likely to come up as a question in the course of a PM's career.
- They are more likely to visit this site for the answer than a site dedicated to second order derivatives and ring theory.
- Fellow PM's are more likely to see the context the question was asked in & tie it back to management practices that may be related.
It might be off-topic because
- It's more likely to get a complete, accurate and timely response from the math community
- It's a math question
- You can google the answer in 5 seconds