Theorem of the Day (February 7, 2026) : A Theorem of Schur on Real-Rootedness
Source : Theorem of the Day / Robin Whitty
pdf : https://www.theoremoftheday.org/Analysis/SchurRealZeros/TotDSchurRealZeros.pdf
notes : https://www.theoremoftheday.org/Resources/TheoremNotes.htm#148
![Comprehensive presentation of the "Theorem of the Day", starting with a statement of this theorem.
A Theorem of Schur on Real-Rootedness : Let f (x) = a0 +a1 x+. . .+am x^m and g(x) = b0 +b1 x+. . .+bn x^n be polynomials in R[x] and suppose that f and g have only real zeros and that all the zeros of g have the same sign. Then the polynomial f (x) ⊙ g(x) = ∑_(k=0)^(min(m,n)) k!ak bk x^k has only real zeros and if a0 and b0 are both nonzero then these zeros are distinct.](https://files.mastodon.social/cache/media_attachments/files/116/028/998/186/592/864/small/f82b04a77fe56368.png)






