How to input math fomula with multiple lines?

[gogdizzy]

$$ s=(p,v,a) \ u=j $$

will got error: KaTeX parse error: Expected 'EOF', got '\' at position 10: s=(p,v,a)\̲\̲ u=j

Thank you

[craftzdog]

Hi @gogdizzy,

Use \begin{aligned}:

\begin{aligned}
\text{A + B = C} \\
\text{C - B = A}
\end{aligned}