Answer
The set of vectors doesn't have a vector space structure, since the second axiom doesn't hold.
Work Step by Step
Let $u = (2,1)$ and let $k=-1$. $u$ is in the set of vectors, but $ku = (-2,-1)$. Since $-2 < -1$, $ku$ is not in the set of vectors. Thus, the second axiom doesn't hold so the set of vectors doesn't have a vector space structure.
