You will need the amssymb package to write the right double arrow symbol in Latex, you can print the symbol in the document using the \rightrightarrows command included in this package.
| Symbol | Right Arrow/U+21C9 |
|---|---|
| Type of symbol | Arrow |
| Package (requirement) | amssymb |
| Argument | No |
| Latex command | \rightrightarrows |
| Example | \rightrightarrows → ⇉ |
\documentclass{article}
\usepackage{amssymb}
\begin{document}
$$ a \rightrightarrows b $$
$$ a_1 \rightrightarrows a_2 $$
\end{document}Output :
