(a) Show how to convert the higher order linear iterative equation
$$
u^{(k+j)}=c_1 u^{(k+j-1)}+c_2 u^{(k+j-2)}+\cdots+c_j u^{(k)}
$$
into a first order system $\mathbf{u}^{(k)}=T \mathbf{u}^{(k)}$. Hint: See Example 9.6.
(b) Write down initial conditions that guarantee a unique solution $u^{(k)}$ for all $k \geq 0$.