# Math Help - PROOF: Pwu = u iff u is in W

1. ## PROOF: Pwu = u iff u is in W

Let W be a subspace of R^n. prove that, for any u in R^n,

Pwu = u iff u is in W

2. Originally Posted by jjs2168
Let W be a subspace of R^n. prove that, for any u in R^n,

Pwu = u iff u is in W
and $P_wu$ is?