Why $\mathbb{R}$ is a subset of $\mathbb{C}$?
77764
Is "$a + 0i$" in every way equal to just "$a$"?
23837
Why is $\mathbb{R}/{\sim}$ not first countable at $[0]$, where $x \sim y \Leftrightarrow x = y\text{ or }x,y \in \mathbb{Z}$?
41013
Subspace of $C^3$ that spanned by a set over C and over R
22464
Which of the following subsets of   $\mathbb{R}^2$ are compact
17525
Why the interior of $\mathbb{Q}$ in $\mathbb{R}$ is empty?
69166
Cardinality of $\mathbb{R}$ and $\mathbb{R}^2$
144246
Subset of $\mathbb{R}^n$ homeomorphic to $\mathbb{R}^n$
90540
What is wrong in this proof: That $\mathbb{R}$ has measure zero
135814
Prove certain subsets of $\mathbb R^n$ are subspaces
112131
Characterizing all ring homomorphisms $C[0,1]\to\mathbb{R}$.
27188
Bijection between $\mathbb{R}$ and $\mathbb{R}/\mathbb{Q}$
70164
Proof exercise that the cardinal number of a set in $\mathbb R^2$ is $\frak c$
110957
No non-trivial clopen sets in $\mathbb{R}$? How to give a direct proof?
143354
Prove that there exists $c\in\mathbb{R}$ such that $f'(c)=f(c)$
74860
Why is the empty set a subset of every set?
74663
Is $\mathbb{R}$ an algebraic extension of some proper subfield?
84148
Why is $\mathbb{R}^2$ not a subspace of $\mathbb{R}^3$?