Show that, after triangularizing \(\mathbf{A x}=\mathbf{y}\), the back substitution method of solving \(\mathbf{A}^{(N-1)} \mathbf{x}=\mathbf{y}^{(N-1)}\) requires \(N\) divisions, \(N(N-1) / 2\) multiplications, and \(N(N-1) / 2\) subtractions. Assume that all the elements of \(\mathbf{A}^{(N-1)}\) and \(\mathbf{y}^{(N-1)}\) are nonzero and real. 6.2}