So I'm trying to understand this statement, which apparently is true...
Let $P=\{ x \in R^n | Ax =b,x \geq 0 \}$ be a polyhedron with matrix $A\in R^{(n-1) \times n}%$ and $rank(A)=n-1$.
P has at most two vertices
I can see this in $R^2$, since it would be just a line and line hast to vertices. but im having a trouble to see it in the general case.. why should it be true? how would it work for n=3?