Prove $|A\cup B| = |A| + |B| - |A \cap B|$
11849
Size of a union of two sets
20878
If $(a,b)=1$ then prove $(a+b, ab)=1$.
145058
Prove $ (A \cup B) \cap C$ = $(A \cap C) \cup (B \cap C) $
101803
A\(B∩C) = (A\B) ∪ (A\C) how to prove?
111763
True or False $A - C = B - C $ if and only if $A \cup C = B \cup C$
14162
How can I prove $\sup(A+B)=\sup A+\sup B$ if $A+B=\{a+b\mid a\in A, b\in B\}$
79165
How to show that $P(A\cup B) = P(A) + P(B) - P(A\cap B)$
86977
If $\cup \mathcal{F}=A$ then $A \in \mathcal{F}$. Prove that $A$ has exactly one element.
115606
Proofs involving $ (A\setminus B) \cup (A \cap B)$
140440
Proving $(A\times C)\cup(B\times D)\subseteq(A\cup B)\times(C\cup D)$
47434
Proof that $A \subseteq B \Leftrightarrow A \cup B = B$
13415
How to show if $A \subseteq B$, then $A \cap B = A$?
75863
how to prove $f^{-1}(B_1 \cap B_2) = f^{-1}(B_1) \cap f^{-1}(B_2)$
87327
Unions and intersections: $(A \cup B = A ∪ C) \land (A \cap B = A ∩ C) \implies B = C.$
52787
If $\bigcup F = A$ then $A\in F$ then prove that $A$ has exactly one element
150738
Proof of $(A - B) - C = A - (B \cup C)$
77361
How to prove $|H|[K:K \cap (g^{-1}Hg)]=|K|[H:H \cap (gKg^{-1})]$?