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Math in Markdown

Markdown has no math of its own, but many tools accept formulas written in LaTeX between dollar signs: GitHub, GitLab, Jupyter notebooks, Obsidian and this editor, which draws them with KaTeX. This page covers the LaTeX you need most. Each example shows the Markdown first and the result under it.

Inline and block math

Put a formula between single dollar signs to keep it in the sentence. Put it between double dollar signs on their own lines to show it centered on a line of its own. 

The area of a circle is $A = \pi r^2$.

$$
E = mc^2
$$

The area of a circle is A = \pi r^2.

E = mc^2

A ```math code block works as a block formula too, as on GitHub.

Superscripts and subscripts

^ raises and _ lowers the next character. Put longer parts in braces: x^{10}, not x^10. 

$x^2$, $x^{10}$, $a_n$, $a_{n+1}$, $e^{-x^2}$

x^2, x^{10}, a_n, a_{n+1}, e^{-x^2}

Fractions and roots

$$
x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}
$$

A cube root: $\sqrt[3]{27} = 3$. A small fraction in text: $\tfrac{1}{2}$.
x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

A cube root: \sqrt[3]{27} = 3. A small fraction in text: \tfrac{1}{2}.

Greek letters

Write the name after a backslash. A capital first letter gives the capital form where it differs from the Latin one.

LaTeX Letter LaTeX Letter LaTeX Letter
\alpha \alpha \theta \theta \sigma \sigma
\beta \beta \lambda \lambda \phi \phi
\gamma \gamma \mu \mu \omega \omega
\delta \delta \pi \pi \Delta \Delta
\epsilon \epsilon \rho \rho \Sigma \Sigma

Operators, relations and arrows

LaTeX Symbol LaTeX Symbol LaTeX Symbol
\times \times \le \le \to \to
\cdot \cdot \ge \ge \Rightarrow \Rightarrow
\div \div \ne \ne \iff \iff
\pm \pm \approx \approx \in \in
\infty \infty \equiv \equiv \subseteq \subseteq

Sums, products, limits and integrals

The bounds go in subscripts and superscripts. In block math they are drawn above and below the symbol. 

$$
\sum_{i=1}^{n} i = \frac{n(n+1)}{2}
\qquad
\prod_{k=1}^{n} k = n!
$$

$$
\lim_{x \to 0} \frac{\sin x}{x} = 1
\qquad
\int_0^1 x^2 \, dx = \frac{1}{3}
$$
\sum_{i=1}^{n} i = \frac{n(n+1)}{2} \qquad \prod_{k=1}^{n} k = n!
\lim_{x \to 0} \frac{\sin x}{x} = 1 \qquad \int_0^1 x^2 \, dx = \frac{1}{3}

\, adds a thin space (before dx), \quad and \qquad wider ones. Spaces you type in a formula are ignored.

Brackets that grow

Plain brackets stay small. \left( and \right) grow to fit what is between them; this works for [ ], \{ \} and | too. 

$$
\left( \frac{a}{b} \right)^2 \quad \text{versus} \quad (\frac{a}{b})^2
$$
\left( \frac{a}{b} \right)^2 \quad \text{versus} \quad (\frac{a}{b})^2

Matrices

Separate columns with & and rows with \\. pmatrix uses round brackets, bmatrix square ones and vmatrix vertical bars (a determinant). 

$$
A = \begin{pmatrix} 1 & 2 \\ 3 & 4 \end{pmatrix}
\qquad
\begin{vmatrix} a & b \\ c & d \end{vmatrix} = ad - bc
$$
A = \begin{pmatrix} 1 & 2 \\ 3 & 4 \end{pmatrix} \qquad \begin{vmatrix} a & b \\ c & d \end{vmatrix} = ad - bc

Aligned equations

Inside aligned, each & marks the point that lines up, and \\ starts a new line. Use it for steps of a calculation. 

$$
\begin{aligned}
(a + b)^2 &= (a + b)(a + b) \\
          &= a^2 + ab + ba + b^2 \\
          &= a^2 + 2ab + b^2
\end{aligned}
$$
\begin{aligned} (a + b)^2 &= (a + b)(a + b) \\ &= a^2 + ab + ba + b^2 \\ &= a^2 + 2ab + b^2 \end{aligned}

Cases

$$
|x| =
\begin{cases}
  x  & \text{if } x \ge 0 \\
  -x & \text{if } x < 0
\end{cases}
$$
|x| = \begin{cases} x & \text{if } x \ge 0 \\ -x & \text{if } x < 0 \end{cases}

Text and fonts in formulas

Letters in a formula are set as variables, in italics. Use \text{…} for words, and the font commands for sets, vectors and other notation. 

$\text{speed} = \frac{\text{distance}}{\text{time}}$,
$x \in \mathbb{R}$, $\vec{v}$, $\mathbf{M}$, $\overline{AB}$, $\hat{y}$

\text{speed} = \frac{\text{distance}}{\text{time}}, x \in \mathbb{R}, \vec{v}, \mathbf{M}, \overline{AB}, \hat{y}

Writing a dollar sign

Two dollar signs in one paragraph can be read as a formula. Put a backslash before a dollar sign that means money. 

The ticket costs \$5, or \$12 for three.

The ticket costs $5, or $12 for three.

Mistakes and limits

A formula with a mistake, such as a missing brace or an unknown command, stays as LaTeX source in color, and pointing at it shows what's wrong; the rest of the document still renders. KaTeX supports most of LaTeX's math, but not whole LaTeX documents or packages. For safety, commands that add links or load images (\href, \url, \includegraphics) are turned off. When you export a document as HTML, its formulas are saved as MathML, which every modern browser can show without extra files.

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