Vector Subspaces, don't understand.... 1. The problem statement, all variables and given/known data Which of the given subsets of the vector space, M23, of all 2 X 3 matrices are subspaces. (a) [a b c, d 0 0] where b = a + c 2. Relevant equations Theorem 4.3 Let V be a vector space with operations + and * and let W be a nonempty subset of V. Then W is a subspace of V if and only if the following conditions hold (a) u and v are any vectors in W, then u + v is in W. (b) If c is any real number and u is any vector in W, then c * u is in W. 3. The attempt at a solution First of all I'm not exactly sure what the space R3 exactly is and what to look for. Is it all the positive numbers in x,y and z? I know what two properties to apply when trying to figure out if its a subspace but I still don't know exactly what to look for. If someone could explain how to look at this problem, anything about vector spaces, or point me in the direction of a good website about them that would be greatly appreciated...i have yet to find one that I like. Thanks!!