Things that may not be obvious - part I - maths

a \cdot b

a \cdot b

\frac{a}{b}

\frac{a}{b}

\begin{cases}
x =\sqrt{2} \\
y =\sqrt[3]{8} \\

\end{cases}

{\begin{cases} x = \sqrt{2} \\ y = \sqrt[3]{8} \end{cases}

a \oplus b || a \odot b

a \oplus b | | a ⊙ b

\bar{a} + \bar{b} + \bar{cd}, but \overline{a+b+cd}

\bar{a} + \bar{b} + \bar{c d}, b u t \overset{―}{a + b + c d}

A \cup B \cap C \in \mathbb{R}^2

A \cup B \cap C \in R^{2}

\lnot a \lor b \land c \implies d \impliedby e

\neg a \lor b \land c ⟹ d ⟸ e

2+1 = 3\iff 3-1 = 2

2 + 1 = 3 ⟺ 3 - 1 = 2

\underset{\underset{jkl}{qwe}}{\overset{\overset{xyz}{def}}{abc}} \equiv \overunderset{def}{qwe}{abc}

\underset{\underset{j k l}{q w e}}{\overset{\overset{z x c}{d e f}}{a b c}} \equiv {a b c}_{q w e}^{d e f}

\begin{align}
x+y&=z\\
x&=z+a\\
0&=2
\end{align}

\begin{aligned} x + y & = z \\ x & = z + a \\ 0 & = 2 \end{aligned}