Prove that the square is not a variety?
97114
Square is not an algebraic set.
36011
Show that the product of two consecutive natural numbers is never a square.
111183
Nonsingular projective variety of degree $d$
108955
Showing $(\mathbb{Q},+)$ is not isomorphic to $(\mathbb{R},+)$
53244
Prove that $p \in \mathbb{R}[x]$ can be represented as a sum of squares of polynomials from $\mathbb{R}[x]$
134120
Prove statement with a counter-example: For all sets S, T and V, V ∪ (S ∩ T) = (V ∪ S) ∩ T is false
4518
How would one go about proving that the rationals are not the countable intersection of open sets?
80671
Product of sums of square is a sum of squares.
55026
$\mathbb{Q}[X,Y]/(Y^2-X^3)$ is not a UFD
79677
Difference of squares - number of representations
149071
Let $d$ be any positive integer not equal to $2, 5,$ or $ 13$ , then $\exists a, b \in \{2, 5, 13, d\}$ such that $ab − 1$ is not a perfect square?
11506
Alternative proof that $(a^2+b^2)/(ab+1)$ is a square when it's an integer
22973
Show that an integer of the form $8k + 7$ cannot be written as the sum of three squares.
106716
The sum of square roots of non-perfect squares is never integer
139288
Formal proof that $e^x$ is not algebraic
93948
Is my proof correct? $p_1p_2p_3\cdots p_n+1)$ cannot be the square of an integer
377
Problem involving many squares and several variables.