Questions askedCategory: 2568Proving subspaces when W is a set of functions of a given degree
To prove $W$ is not a subspace, finding a counter example to any of (S1), (S2), (S3) in Theorem 2 (p.369)is sufficient.
To prove $W$ is a subspace, you need to verify all the subspace criteria in Theorem 2. Check out the following problems and solutions. These should illustrate how to write a solution.