Find the following norms: (Type in exact answers, e.g. sqrt(2) for $\sqrt{2}$.)

(a) $\| \mathbf{u} \|$ for $$\mathbf{u} = \begin{bmatrix} 3 \\ 6 \\ 2 \\ 8\end{bmatrix}.$$

Answer: $\| \mathbf{u} \| =$ .

(b) $\| \mathbf{u} \|$ for $$\mathbf{u} = \begin{bmatrix} 5 \\ 0 \\ -3 \\ 2 \\ -1 \end{bmatrix}.$$

Answer: $\| \mathbf{u} \| =$ .

(c) $\| \mathbf{u} \|$ for $$\mathbf{u} = \begin{bmatrix} 5 + 4i \\ 6 + 7i \\ 5 + 3i \end{bmatrix}.$$

Answer: $\| \mathbf{u} \| =$ .