1. The problem statement, all variables and given/known data use the subspace theorem to decide if the sets is a real vector space with respect to the usual operation the set of all solutions of the homogenous differential equation 7f''(x) +4f'(x) -6f(x) = 0 2. Relevant equations none 3. The attempt at a solution try to put this second order d.e. into first order matrix system. but don't know what to do next. how to proof one matrix is under a vector space?