Originally Posted by

**Harry1W** However, when I paste the LaTeX code into the board here (with the appropriate math tags), I receive a LaTeX syntax error. Why should this be?

I guess it is because of the "eqnarray" environment.

To have your equations correctly displayed you just have to modify the first and the last line :

Code:

\begin{array}{rcl}
x & = & \frac{4}{100}e^{\frac{-1}{100}t}\sin(12t)\\
\: & = & {\rm Re}\left(ce^{\alpha+i\beta}\right)\\
\: & = & {\rm Re}\left(ce^{\alpha}e^{i\beta}\right)\\
\: & = & {\rm Re}\left(ce^{\alpha}\left[\cos\beta+i\sin\beta\right]\right)\\
\: & = & ce^{\alpha}\cos\beta\\
\frac{4}{100}e^{\frac{-1}{100}t}\sin(12t) & = & ce^{\alpha}\sin\left(\beta+\frac{\pi}{2}\right)
\end{array}

Another solution would be to use the "aligned" environment :

Code:

\begin{aligned}
x & = \frac{4}{100}e^{\frac{-1}{100}t}\sin(12t)\\
& = {\rm Re}\left(ce^{\alpha+i\beta}\right)\\
& = {\rm Re}\left(ce^{\alpha}e^{i\beta}\right)\\
& = {\rm Re}\left(ce^{\alpha}\left[\cos\beta+i\sin\beta\right]\right)\\
& = ce^{\alpha}\cos\beta\\
\frac{4}{100}e^{\frac{-1}{100}t}\sin(12t) & = ce^{\alpha}\sin\left(\beta+\frac{\pi}{2}\right)
\end{aligned}