I have this equation and it's quite big (basically a FDM one) but it aligns with the text and then continues out on the right side to the nothingness. I've tried stuff like \begin{center} and \hspace*{-2.5cm} but to no avail. I want it to use the whole line not just from the left-margin and out to the right.

How do I do it and do I need to install some special package for it?

I use the \[ instead of the displaymath like this

\[
  Equation arrays here
\]

The code

\[
 \left(
   \begin{array}{cccccc}
      -(2\kappa+\frac{hV\rho}{2}) & (\frac{hV\rho}{2}-\kappa) & 0 & \cdots  & 0 \\
      -\kappa & -(2\kappa+\frac{hV\rho}{2}) & (\frac{hV\rho}{2}-\kappa) & 0 & \cdots \\  
      0 & -\kappa & -(2\kappa+\frac{hV\rho}{2}) & (\frac{hV\rho}{2}-\kappa) & 0 & \cdots \\  
      \vdots  & 0  & \ddots & \vdots  \\
      \vdots & \vdots  & \vdots  & -\kappa & -(2\kappa+\frac{hV\rho}{2}) & (\frac{hV\rho}{2}-\kappa) \\  
      0 & \vdots  & \vdots  & 0 & \kappa - \frac{2h\kappa_{v}}{\kappa}(\frac{hv\rho}{2} - \kappa) & -2\kappa \\  
   \end{array} 
 \right)
 \left(
   \begin{array}{c}
      T_{1} \\
      T_{2} \\
      \vdots \\
      T_{n} \\
   \end{array} 
 \right)
 =  
 \left(
   \begin{array}{c}
      Q(0) + \kappa T_{0} \\
      Q(h) \\
      Q(2h) \\
      \vdots \\
      Q((n-1)h) \\
      2\frac{\kappa_{v}}{\kappa_{v}}T_{out} \\
   \end{array} 
 \right)  
\]