$\{ a + b\sqrt{2} \ : \ a, b \in \mathbb{Z} \}$ dense in $\mathbb{R}$?
29965
Proving that $m+n\sqrt{2}$ is dense in $\mathbb R$
31436
Show that for all $a\in\mathbb{N}$, there exists $b\in\mathbb{N}$ and square-free integer $c$ such that $\sqrt{a}=b\sqrt{c}$.
141799
Is $2^{|\mathbb{N}|} = |\mathbb{R}|$?
121831
Proving that rational numbers are dense
63478
Is $\mathbb{Q}(\sqrt{2}) \cong \mathbb{Q}(\sqrt{3})$?
91113
$ \exists a, b \in \mathbb{Z} $ such that $ a^2 + b^2 = 5^k $
131060
Is $\sqrt{x}$ uniformly continuous in $\mathbb{R}^+$?
78082
Dense subset of two Banach spaces also dense in the intersection
133775
Is $\mathbb{Z}[\sqrt{-7}]$ a UFD or not?
66272
Is there a common notion of $\mathbb{R}^n$, for non-integer $n$?
31295
$x+y\sqrt{2}$ infimum ($x,y\in \mathbb{Z}$)
48162
Is the subset $[0, \sqrt2] ∩\mathbb{Q} ⊂ \mathbb{Q}$ closed, bounded, compact?
33309
Subgroup of $\mathbb{R}$ either dense or has a least positive element?
35105
Density of ring of algebraic integers in $\mathbb C$
11935
Is $\mathbb{Z} \left[ \frac{1+i \sqrt{7}}{2} \right]$ euclidean?
90826
Constructing a subset not in $\mathcal{B}(\mathbb{R})$ explicitly
95294
Dense subset of $C[0,1]$ which preserves rationals