1. The problem statement, all variables and given/known data My question is if u+v is in the subspace can you say that u or v is in the subspace? If not would there be a counterexample? 2. Relevant equations closed under addition/scalar multiplication 3. The attempt at a solution I know that if u or v were in the subspace they would be closed under addition or multiplication. I don't know if you can say the same for (u+v) and apply it just to u or v. Thank you for any help.