How to Write Equations in LaTeX

To write equations in LaTeX, use $...$ for inline math (e.g. $E=mc^2$) and the equation environment for numbered display math: \begin{equation} ... \end{equation}. Load amsmath with \usepackage{amsmath} for fractions (\frac), alignment (align), and advanced symbols. LetX renders math live as you type.

Step by step

Load amsmath

Add \usepackage{amsmath} for the best math support.

Inline math

Wrap math in $...$ to keep it in the text line, e.g. $a^2 + b^2 = c^2$.

Display math

Use \begin{equation} ... \end{equation} for a centered, numbered equation.

Align multiple lines

Use the align environment with & alignment points and \\ between lines.

Compile

Compile to PDF; LetX shows rendered math in the live preview in seconds.

Example

\usepackage{amsmath}
% Inline: the identity $e^{i\pi} + 1 = 0$.
\begin{equation}
  \frac{\partial f}{\partial x} = 2x
\end{equation}
\begin{align}
  a &= b + c \\
    &= d
\end{align}

Use \frac{a}{b} for fractions, x^{2} for superscripts, x_{i} for subscripts, and \sum, \int, \sqrt{} for common operators.

Symbol cheat sheet

You want	Command	You want	Command
α β γ	\alpha \beta \gamma	± × ÷	\pm \times \div
≤ ≥ ≠	\leq \geq \neq	≈ ≡ ∝	\approx \equiv \propto
∞ ∂ ∇	\infty \partial \nabla	→ ⇒ ↦	\to \Rightarrow \mapsto
∈ ⊂ ∪ ∩	\in \subset \cup \cap	∀ ∃ ¬	\forall \exists \neg
∑ ∏ ∫	\sum \prod \int	x̄ x̂ ẋ	\bar x \hat x \dot x

Matrices

\begin{equation}
  A = \begin{pmatrix}  % p=() b=[] v=|| B={}
    1 & 2 \\
    3 & 4
  \end{pmatrix}
\end{equation}

Piecewise functions (cases)

\begin{equation}
  f(x) = \begin{cases}
    x^2 & \text{if } x \geq 0 \\
    -x  & \text{otherwise}
  \end{cases}
\end{equation}

Note \text{...} from amsmath. It keeps words upright inside math mode instead of italicizing them as variables.

Long derivations with align

\begin{align}
  (a+b)^2 &= (a+b)(a+b) \\
          &= a^2 + ab + ba + b^2 \nonumber  % suppress one number
          \\
          &= a^2 + 2ab + b^2
\end{align}

The & marks the alignment column (usually before =); \nonumber or the starred align* suppresses equation numbers.

Frequently asked questions

What is the difference between equation and align?

equation is for a single numbered equation; align is for multiple equations aligned at a chosen point (the &), each numbered unless you use align*.

How do I write an unnumbered equation?

Use the starred version: \begin{equation*} ... \end{equation*}, or use \[ ... \] for quick display math.

How do I write a fraction in LaTeX?

Use \frac{numerator}{denominator}, e.g. \frac{1}{2}. For inline fractions in text, \tfrac gives a smaller, text-sized fraction.

How do I write a matrix in LaTeX?

Use the pmatrix environment from amsmath: \begin{pmatrix} 1 & 2 \\ 3 & 4 \end{pmatrix}. Variants: bmatrix for [brackets], vmatrix for |determinants|, Bmatrix for {braces}.

How do I put normal text inside an equation?

Use \text{...} from amsmath: f(x) = x^2 \text{ for } x > 0. Without it, LaTeX italicizes the words as if each letter were a variable.

How do I number equations by section?

Add \numberwithin{equation}{section} (amsmath) to the preamble, equations then number as (2.1), (2.2) per section.

Why does my equation overflow the page margin?

Long equations need manual breaking: use the multline environment, or split inside align across several lines at sensible operators.