[Tugindia] equation- how to

[S. venkataraman]

Hi,
The explanation is that inside mbox, latex is no
longer in the math mode and it encounters something
which can be used only in math mode. So, it protests.
Try some thing like the following instead:
\left\{
\begin{array}{l}
\begin{array}{rcl}
\mu (\nabla u , \nabla v) &=& (f,v)
\end{array}
\begin{array}{rcl}
(\nabla \cdot{u},q) &=& 0
\end{array}
\end{array}
\right.

With best regards,
S. Venkataraman

seems to be simple but didnt have any success

i want to have two equations aligned (without numbes) inside a left
bracket "{ "
i tried like following (please understand i dont have much experience
using latex... so might be wierd way--)

 \left\{
\begin{array}{l}
\mbox
{
\begin{equation*}
\mu (\nabla u , \nabla v) &=& (f,v)
\end{equation*}
}
\mbox
{
\begin{equation*}
(\nabla \cdot{u},q) &=& 0
\end{equation*}
}
\end{array}
\right.

it didnt work..
and i also have some questions on how to interpret some of the  error
messages.
for example when i tried the above tex thrown some error message  like
following:

! Missing $ inserted.
<inserted text>
                $
l.42  \left
           \{
?

now my question is whats the meaning of
! Missing $ inserted. (what should i make it from this)
and etc..
sorry if i am being so stupid in sending these kind of silly
questions... excuse me

thanks for your help.

Sreejith