x1 - x2 - x3 = 7

x1 - x2 - 2x3 = 2

I know how to solve the problem, but I don't know how to show it geometrically so here is the answer:

$\displaystyle \left(\begin{array}{cc}x1\\x2\\x3\end{array}\right )$ = x2$\displaystyle \left(\begin{array}{cc}1\\1\\0\end{array}\right)$ + $\displaystyle \left(\begin{array}{cc}12\\0\\5\end{array}\right)$

How do you graph this? Help please

Thank You