LaTeX.org

As I guess, there was a simple thing... thanks for helping.

Luso

Hi all,

This is the first time I need to post and that's cool. It means I've found the 100E16 answers needed before... and thanks to you xD.

But now I found four of this => Error: ! Missing $ inserted at lines 3 and 4 on the code, what is wrong?
\begin{equation}
\left(
\begin{array}{cc}
$R_{3 ...