(basic) Equation support on unmet hours

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To see how any formula was written in any question or answer, including this one, right-click on the expression it and choose "Show Math As > TeX Commands".

For inline formulas, enclose the formula in $...$. For displayed formulas, use $$...$$. These render differently: $\sum_{i=0}^n i^2 = \frac{(n^2+n)(2n+1)}{6}$ (inline) or $$\sum_{i=0}^n i^2 = \frac{(n^2+n)(2n+1)}{6}\tag{displayed}$$

For Greek letters, use \alpha, \beta, …, \omega: $\alpha, \beta, … \omega$. For uppercase, use \Gamma, \Delta, …, \Omega: $\Gamma, \Delta, …, \Omega$.

For superscripts and subscripts, use ^ and _. For example, x_i^2: $x_i^2$.

Groups. Superscripts, subscripts, and other operations apply only to the next “group”. A “group” is either a single symbol, or any formula surrounded by curly braces {…}. If you do 10^10, you will get a surprise: $10^10$. But 10^{10} gives what you probably wanted: $10^{10}$. Use curly braces to delimit a formula to which a superscript or subscript applies: x^5^6 is an error; {x^y}^z is ${x^y}^z$, and x^{y^z} is $x^{y^z}$. Observe the difference between x_i^2 $x_i^2$ and x_{i^2} $x_{i^2}$.

Parentheses Ordinary symbols ()[] make parentheses and brackets $(2+3)[4+4]$. Use \{ and \} for curly braces ${}$.

These do not scale with the formula in between, so if you write (\frac{\sqrt x}{y^3}) the parentheses will be too small: $(\frac{\sqrt x}{y^3})$. Using \left(…\right) will make the sizes adjust automatically to the formula they enclose: \left(\frac{\sqrt x}{y^3}\right) is $\left(\frac{\sqrt x}{y^3}\right)$.

\left and\right apply to all the following sorts of parentheses: ( and ) $(x)$, [ and ] $[x]$, \{ and \} $\lbrace x \rbrace$, | $|x|$, \langle and \rangle $\langle x \rangle$, \lceil and \rceil $\lceil x \rceil$, and \lfloor and \rfloor $\lfloor x \rfloor$. There are also invisible parentheses, denoted by .: \left.\frac12\right\rbrace is $\left.\frac12\right\rbrace$.

Sums and integrals \sum and \int; the subscript is the lower limit and the superscript is the upper limit, so for example \sum_1^n $\sum_1^n$. Don't forget {…} if the limits are more than a single symbol. For example, \sum_{i=0}^\infty i^2 is $\sum_{i=0}^\infty i^2$. Similarly, \prod $\prod$, \int $\int$, \bigcup $\bigcup$, \bigcap $\bigcap$, \iint $\iint$.

Fractions There are two ways to make these. \frac ab applies to the next two groups, and produces $\frac ab$; for more complicated numerators and denominators use {…}: \frac{a+1}{b+1} is $\frac{a+1}{b+1}$. If the numerator and denominator are complicated, you may prefer \over, which splits up the group that it is in: {a+1\over b+1} is ${a+1\over b+1}$.

Fonts

• Use \mathbb or \Bbb for "blackboard bold": $\mathbb{CHNQRZ}$.
• Use \mathbf for boldface: $\mathbf{ABCDEFGHIJKLMNOPQRSTUVWXYZ}$ $\mathbf{abcdefghijklmnopqrstuvwxyz}$.
• Use \mathtt for "typewriter" font: $\mathtt{ABCDEFGHIJKLMNOPQRSTUVWXYZ}$ $\mathtt{abcdefghijklmnopqrstuvwxyz}$.
• Use \mathrm for roman font: $\mathrm{ABCDEFGHIJKLMNOPQRSTUVWXYZ}$ $\mathrm{abcdefghijklmnopqrstuvwxyz}$.
• Use ...