1. The problem statement, all variables and given/known data Let u be a vector where u = [4 3 1]. Let A be the set of all vectors orthogonal to u. Show that A is subspace of R^3. Then find the basis for A. 2. Relevant equations 3. The attempt at a solution For showing that A is a subspace... Zero vector is in A because A(0) = 0 For any u & v, u+v is in A because Au=0, Av=0, and A(u+v) = Au+Av = 0 And for any scalar c, A(cu) = c(Au) = c(o) = 0 As for the basis, I really have no idea where to even start with that. Thanks for any help.