Prove A or (A and B) is equivalent to A
121361
Showing that $\lnot Q \lor (\lnot Q \land R) = \lnot Q$ without a truth table
143979
How can I prove that $|A| + |B| = |A\cup B| + |A\cap B|$?
86030
Prove or disprove - If a divides b and b divides a does a=b
21250
Prove $x \equiv a \pmod{p}$ and $x \equiv a \pmod{q}$ then $x \equiv a\pmod{pq}$
151852
How to prove $A \subset B \iff A \cup B = B$
24098
Prove that $a$ divides $b$ and $b$ divides $a$ if and only if $a = \pm b$
145719
Similarity between $A$ and $B (2\times 2)$.
145058
Prove $ (A \cup B) \cap C$ = $(A \cap C) \cup (B \cap C) $
60707
Show that if $ \ A \cup B = A$ and $ \ A\cap B = A$ then $ \ A = B$
113065
Proving equivalences of statements equivalent to AC
83714
$A \in B$ vs. $A \subset B$ for proofs
149287
Prove that $A,B>0$ and $A_{ij}0$
21737
If $A|B$ and $B|A$ then prove $A=\pm B$
127296
prove that a|b and b|a iff a=+-b
119156
$(a,b)=d \overset{?}{\implies} (a^3,b^3)=d^3$
83996
For any two sets $A,B$ , $|A|\leq|B|$ or $|B|\leq|A|$
62936
Proving equivalencies of two versions of the Axiom of Choice