Chapter 11 - Section 11.1 - Sequences - Exercise Set - Page 640: 51

$d=\sqrt{13} \text{ units} $

Using the Distance Formula, $d=\sqrt{(x_1-x_2)^2+(y_1-y_2)^2}$, the distance between $ (-4,-1) \text{ and } (-7,-3) $ is \begin{array}{l} d=\sqrt{(-4-(-7))^2+(-1-(-3))^2} \\\\ d=\sqrt{9+4} \\\\ d=\sqrt{13} \text{ units} .\end{array}