Differences of $V_1 \cup V_2$ and $V_1 +V_2$?
11301
Union of two vector subspaces not a subspace?
148234
Express set $[a,b] \cup [c,d]$ as the difference of two intervals
127000
When does $V = \ker(f) \oplus \operatorname{im}(f)$?
61666
Proving $ [(\vec{a}+\vec{b})\times(\vec{b}+\vec{c})]\cdot(\vec{c}+\vec{a})=2\vec{c}\cdot(\vec{b}\times\vec{a})$
148668
How to show $A\times (B\cup C) = (A\times B)\cup (A\times C)$
17508
Knowing $|z|$ and $|w|$ (and possibly $z\overline{w}$), what are $|z+w|^2$, $|zw|^2$, $|z-w|^2$, $|z/w|^2$?
26302
Prove that $(X \cap Y) \cup Z = (X \cup Z) \cap (Y \cup Z)$
27898
Difference between $\sqrt{x^2}$ and $(\sqrt{x})^2$
79677
Difference of squares - number of representations
158852
If $\{v_1, v_2, v_3\}$ is an orthonormal basis of $\mathbb{R}^3$ and $v = a_1v_1 + a_2v_2 + a_3v_3$, can we have $|a_1| > 3$?
71767
What is the difference between $\Bbb{R^n}\times\Bbb{R^m}$ and $\Bbb{R^{m+n}}$?
92291
$U_1, U_2, ..., U_k$ subspaces of linear space $X$ with same dimensions, prove $X=U_1\oplus V=U_2\oplus V=...=U_k\oplus V$
76610
Show that $f^{-1}(A \cup B) = f^{-1}(A) \cup f^{-1}(B)$
104258
Proof Verification: $\dim\mathrm{Im} T+\dim\ker T=\dim V$
131998
let ${v_1}, {v_2} $ be orthonormal basis for subspace $W$. Prove that if $z$ is a vector in $W$, then
145462
On the canonical isomorphism between $V$ and $V^{**}$
58113
Av = Bv for all v implies A = B?