Sum and product of algebraic numbers
24551
How to prove that the sum and product of two algebraic numbers is algebraic?
146047
Proving that $\cos(2\pi/n)$ is algebraic
79679
Let $\alpha, \beta \in \mathbb{C}$, such that $\alpha + \beta$, and $\alpha\beta$ are algebraic. Show that $\alpha$ and $\beta$ are algebraic.
4401
Constructive proof that algebraic numbers form a field
1519
Sum of derivatives of a polynomial
78309
On an expansion of $(1+a+a^2+\cdots+a^n)^2$
21972
How to show that $\sqrt{2}+\sqrt{3}$ is algebraic?
35765
product of two numbers ending in 6 also ends with 6
26330
Why can we modular reduce arguments of sums and products in modular arithmetic?
137967
Are there $a,b \in \mathbb{N}$ that ${(\sum_{k=1}^n k)}^a = \sum_{k=1}^n k^b $ beside $2,3$
1379
Summation of $n^2x^n$ terms
80671
Product of sums of square is a sum of squares.
16548
Prove $(x+y) \text{ mod } n = ((x \text{ mod } n)+(y \text{ mod } n)) \text{ mod } n,\,$ and product analog
20309
Product and sum of positive operators is positive
57986
Sum of products of combinatorials
26908
Partial Sums of Geometric Series
147562
Sum of squares diophantine equation