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Interesting Math Questions (Math SE and MathOverflow)
A function with positive 𝑛-th derivative has at most 𝑛 roots – an inequality version of the Fundamental theorem of Algebra.
How many strict local minima a quartic polynomial in two variables might have?
Can a cubic polynomial in two real variables have three saddle points?
How many saddle points can a quartic polynomial in two real variables have? All 9?
Math serources for students (Econ SE):