What should be the .tex command given for this large bracket.

 

It's just an opening brace. TeX will enlarge it if there are multiple lines inside the brace.

TeX Examples

 

could please type it .tex file that for me..I mean the format.I am not able to make it in this form .Thank you

 

From my sigline...

Testing a big TeX block: Everything below is in one tag, works OK:

\(f(z) = \left\{ \begin{array}{rcl}
\overline{\overline{z^2}+\cos z} & \mbox{for}
& |z|<3 \\ 0 & \mbox{for} & 3\leq|z|\leq5 \\
\sin\overline{z} & \mbox{for} & |z|>5
\end{array}\right
\
\left( \begin{array}{cc} 2\tau & 7\phi-32\theta \\
3\psi & \frac{\pi}8 \end{array} \right)
\left( \begin{array}{c} x \\ y \end{array} \right)
\mbox{~and~} \left[ \begin{array}{cc|r}
3 & 4 & 5 \\ 1 & 3 & 729 \end{array} \right]\)

Quote post to see the TeX code.