I want to write the shown mathematical equation in LaTeX but I am getting an error. Here this is not eta but it is n
. The code which I am writing is
\begin{equation}
\Delta {E} + \frac{\omega^2 n$_{i}$^2}{c^2} E = 0
\end{equation}
Your code incorrectly contains dollar signs, which are not allowed directly in a math display:
\documentclass{article}
\begin{document}
Suppose \( E \) satisfies the following differential equation
\begin{equation}
\Delta E + \frac{\omega^2 \eta_i^2}{c^2} E = 0.
\end{equation}
\end{document}
The curly brackets {...}
around the first E
are unnecessary. On the other hand you might consider writing brackets around super- and subscripts:
\omega^{2} \eta_{i}^{2}
so you don't get surprised when you have more complicated material in these positions.
\omega^{2} n_{i}^{2}
will do.n
but\eta
.