Closure under vector adition
Closure under scalar multiplication (similarly)
"Let V be a vector space, and let W1 and W2 be subspaces of V. Prove that (W1 ^ W2) is a subspace of V."
by ^ I mean the intersection of W1 and W2.
I'm not sure how to do this... (W1 ^ W2) is obviously a subset of V but how do you prove it has closure under vector addition and scalar multiplication?