Show that every subgroup of $ ( \Bbb{R} ,+)$ is cyclic or dense
26256
Characterizing Dense Subgroups of the Reals
92740
prove that $\mathbb{Q}^n$is dense subset of $\mathbb{R^n}$
158011
$C_c^{\infty}(\mathbb R^n)$ is dense in $W^{k,p}(\mathbb R^n)$
128652
Subgroups of $\mathbb Z \times(\mathbb Z/n\mathbb Z)$
146760
Prove that H is a subgroup of G
135039
${\rm Aut}(G)$ is cyclic $\implies G$ is abelian
39938
Subgroups of a cyclic group and their order.
25795
Density of $\mathbb{Q}^n$ in $\mathbb{R}^n$
138297
Let $G = GL_2\mathbb (R)$. Show that $T$ is a subgroup of $G$
84823
When is the group of units in $\mathbb{Z}_n$ cyclic?
33945
Showing that $|N \cap Z(G)| > 1$ for normal subgroups of p-groups
149578
Subgroups of $(\mathbb Z_n,+)$
5996
Are $(\mathbb{R},+)$ and $(\mathbb{C},+)$ isomorphic as additive groups?
101602
consider the group $G=\mathbb Q/\mathbb Z$. For $n>0$, is there a cyclic subgroup of order n
90590
Prove that the following set is dense
13734
Show that every group of prime order is cyclic
142894
Showing that a group of order $pq$ is cyclic if it has normal subgroups of order $p$ and $q$