$13 . $ (d) True or false. Give reason. (i) The union of two subspaces of a vector space $V(F)$ is a subspace of $V$. (ii) The vector $(2,-5,3) $ belongs to the subspace of $R^{3} $ spanned by the vectors $(1,3,-2), (2,-4,-1),(1, -5,7)$. (6) Can the set $S=\{(1,0,0),(1,1,0), (4,5,0) U}$ be extended to form a basis of $R^{4} (R) $ ? CS.VS. 1724 9