11. 2.c. let u = {p ∈ p4(r) | p ′′′(0) = 0 and p ′′(1) = 0}. (a) find a basis of u. (b) extend the basis in part (a) to a basis of p4(r). (c) find a subspace w of p4(r) such that p4(r) = u ⊕ w