Prove that $A \Delta (B \Delta C) = (A \Delta B) \Delta C$.
12459
Associativity of symmetric difference of sets
105108
How to show this sequence is a delta sequence?
124868
Prove that $\frac{bc}{b+c}+\frac{ca}{c+a}+\frac{ab}{a+b}<\frac{a+b+c}{2}$
29935
If $a, b, c, d>0$ and $abcd=1$ prove that an inequality holds true
43462
Disprove $\mathcal{P}(A\Delta B) \setminus \{\emptyset\} = \mathcal{P}(A) \Delta\mathcal{P}(B) $. Is my proof good?
46106
Prove that $D_r \circ D_s = \{ (x,y) \in \mathbb{R}^2 \ | \ |x-y|<r+s \}$, where $D_a = \{ (x,y) \in \mathbb{R}^2\ | \ |x-y| < a \}$
80789
Prove that $\forall a,b,c,d\in \mathbb{R}\,$, $(a^2-b^2)(c^2-d^2)\leq(ac-bd)^2$ and equalities hold if and only if $ad=bc$.
132873
Understanding Epsilon-Delta Proof
53610
What is the difference between $Q=\Delta U+W$ and $\Delta U=Q+W$?
143979
How can I prove that $|A| + |B| = |A\cup B| + |A\cap B|$?
80876
Proof of $A\cap(B\cup C) = (A\cap B)\cup(A\cap C)$
13136
Element chasing proof that $(A\setminus C)\setminus(B\setminus C) = (A\setminus B)\setminus C$
111003
Prove that if $A\triangle B = C\triangle B$, then $A = C$
145058
Prove $ (A \cup B) \cap C$ = $(A \cap C) \cup (B \cap C) $
95852
Prove that $(a+b)(b+c)(c+a) \ge8$
57125
Prove the distributive law $a(b+c)=ab+ac$ for real numbers?
81794
Prove that $(ab,cd)=(a,c)(b,d)\left(\frac{a}{(a,c)},\frac{d}{(b,d)}\right)\left(\frac{c}{(a,c)},\frac{b}{(b,d)}\right)$