Why is $-a \times -b = ab$?
17515
Why is negative times negative = positive?
45213
Easiest and most complex proof of $\gcd (a,b) \times \operatorname{lcm} (a,b) =ab.$
108325
What's the relationship between $SL(2,\mathbb{C})$, $SU(2)\times SU(2)$ and $SO(1,3)$?
18800
If A and B are symmetric is AB=BA true?
109710
Bijection between $\mathbb N \times \mathbb N$ and $\mathbb N$
83713
If $z,w\in \mathbb{C}^{\times}$, then $|z+w|=|z|+|w|$ iff $w=tz$ for some $t\gt 0$
116866
$A\times B$ connected component implies $A,B$ connect components
81868
How to prove $\operatorname{Tr}(AB) = \operatorname{Tr}(BA)$?
13012
Why can a = b imply 2 = 1?
62474
If $AB=I_n$ and $BA=I_m$ then $n=m$.
98901
What's wrong with this argument for finding Aut($\mathbb{Z_p} \times \mathbb{Z_p}$)?
38428
How tot start proving $A \times B \times C \ne (A \times B) \times C$?
6650
Why $\sqrt{-1 \times -1} \neq \sqrt{-1}^2$?
72092
If $A^2 = I$, $B^2=I$ and $(AB)^2=I$, then $AB = BA$
80684
Counter example for $(A \times B) \cap (C \times D) = (A \cap C ) \times (B \cap D)$
37061
The order of $ab$ when $a,b$ commute
150320
Why does $a^{b}·a^{c}=a^{b+c}$?