Subsets and subspaces, perpendicular sets!

M is a subset of R^n. M* is a set of vectors which are perpendicular to M (ie each element of M* is perpendicular to each element of M).

Firstly: Show that M* is a subspace of R^n

Secondly : In R^3, find M* where M = {2i-j+2k,i-2j-2k}

Quote:

---

Originally Posted by flawless

M is a subset of R^n. M* is a set of vectors which are perpendicular to M (ie each element of M* is perpendicular to each element of M).

Firstly: Show that M* is a subspace of R^n

Secondly : In R^3, find M* where M = {2i-j+2k,i-2j-2k}

---

Firstly:
Let ,

(+)

(.)