Equation of the Plane I have been working through all the problems in my textbook and I have finally got to a difficult one.
The problem ask 

Find the equation of the plane.The plane that passes through the points $(-1,2,1)$ and contains the line of intersection of the planes $x+y-z =2$ and $2x-y+3z=1$

So far I found the direction vector of the line of intersection to be $<1,-2,1>$ and I have identified a point on this line when $x=0$ to be $(0,5,-1)$. 
I do not know how to find the desired plane from here.
Any assistance would be appreciated.

The following determinant is another form of what Scott noted: $$\begin{vmatrix}
(x-x_0)&  (y-y_0)&  (z-z_0)\\1&  1&  -1\\2&  -1&  3
\end{vmatrix}$$
