How to work out as in picture!

Question

Can you show me how to work out as in picture? Thank you!

Answer 1

Use aligned from the amsmath package. You seem to struggle with the very basics of LaTeX. Therefore please also see these two questions:

• What are good learning resources for a LaTeX beginner?

• LaTeX Introductions in languages other than English

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{equation}
  \begin{aligned}
    -\Delta u &= \mu p(x,u), && x \in \Omega \\
    u &= 0, && x \in \partial\Omega,
  \end{aligned}
\end{equation}
\end{document}