# Linear Algebra Question

1. Nov 18, 2006

### CaityAnn

I have three systems of equations:
x+y+2z=a , x+z= b and 2x+y+3z=c
Show that in order for this system to have at least one solution, a,b,c must satisfy c=a+b.

Obviously I can add the equations a and b and get c. But I dont know how else to approach showing this. I think the points of x,y,z of c must satisfy both a,b and provide a solution set for both but Im not sure how to prove that. HELP PLEASE~!

2. Nov 19, 2006

$$\begin{bmatrix} 1 & 1 & 2 & a \\ 1 & 0 & 1 & b \\ 2 & 1 & 3 & c \\ \end{bmatrix}$$