2. A natural cubic spline with k knots is represented by k basis functions: N1(x) = 1, N2(x) = x, N;+2(x) = dj(x) dk-1(x) for j = 1, ..., k 2 where _ ((x $j)+)3 ((x k)+)3 8k - &; Show that Nk" = 0. 2. A natural cubic spline with k knots is represented by k basis functions: N1(x) = 1, N2(x) = x, N;+2(x) = dj(x) dk-1(x) for j = 1, ..., k 2 where _ ((x $j)+)3 ((x k)+)3 8k - &; Show that Nk" = 0