$P,Q,R$ be subspaces of a vector space $V$ such that $V=P \cup Q \cup R$ , then must one of $P,Q,R$ be equal to $V$?
15560
Prove that the union of three subspaces of $V$ is a subspace iff one of the subspaces contains the other two.
26497
Take $\mathbb{R}$ as a vector space over $\mathbb{Q}$, then a basis for $\mathbb{R}$, then $|B|=2^{\aleph_0}$
146339
Proof of -(-v)=v in a vector space
92291
$U_1, U_2, ..., U_k$ subspaces of linear space $X$ with same dimensions, prove $X=U_1\oplus V=U_2\oplus V=...=U_k\oplus V$
19396
For subspaces, if $N\subseteq M_1\cup\cdots\cup M_k$, then $N\subseteq M_i$ for some $i$?
67709
Stuck with proof for $\forall A\forall B(\mathcal{P}(A)\cup\mathcal{P}(B)=\mathcal{P}(A\cup B)\rightarrow A\subseteq B \vee B\subseteq A)$
112205
Which of the following polynomials are subspaces of $\mathbb{P}_n$ for an appropriate value of n?
123665
A question in Subspaces in linear algebra
102458
Subspace generated by permutations of a vector in a vector space
59531
Do $T$-invariant subspaces necessarily have a $T$-invariant complement?
134065
A question about an $n$-dimensional subspace of $\mathbb{F}^{S}$.
149553
Is it always true that $(A_1 \cup A_2) \times (B_1 \cup B_2)=(A_1\times B_1) \cup (A_2 \times B_2)$
91022
How do I prove that a subspace of a vector space $X$ is the null space of some linear functional on $X$?
151161
norms on vector space are equivalent iff they have same topology
146143
Question about proof that finite-dimensional subspaces of normed vector spaces are direct summands
54217
Let $V$ be a vector space. Determine all linear transformations $T:V \rightarrow V$ such that $T=T^2$.
95227
Is the set of all $n\times n$ matrices, such that for a fixed matrix B  AB=BA, a subspace of the vector space of all $n\times n$ matrices?