1. The problem statement, all variables and given/known data Determine whether the set of polynomials of degree 3 form a subspace of P(4) 2. Relevant equations [tex]P(4) = c_3 x^3 + c_2 x^2 + c_1 x + c_0[/tex] 3. The attempt at a solution [tex]\alpha P(4_1) = \alpha c_3 x^3 + \alpha c_2 x^2 + \alpha c_1 x + \alpha c_0[/tex] This just scales the coefficients, right? It would still be a polynomial of degree 3 I think... For addition, wouldn't you just be adding two polynomials? So wouldn't you just obtain another degree 3 polynomial? Thanks, Sean.