Exercise 20

Find \(\mathbf{a} + \mathbf{b}, 4\mathbf{a} + 2\mathbf{b}, |\mathbf{a}|,\) and \(|\mathbf{a} - \mathbf{b}|\). \(\mathbf{a} = 5\mathbf{i} + 3\mathbf{j}, \mathbf{b} = -\mathbf{i} - 2\mathbf{j}\)