Chapter 9 - Polar Coordinates; Vectors - 9.3 The Complex Plane; De Moivre's Theorem - 9.3 Assess Your Understanding - Page 595: 73

$5\sqrt2$ units

The distance formula from $P_1(x_1, y_1)$ to $P_2(x_2, y_2)$ is $d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}$. Hence, here we have $d=\sqrt{(-3-2)^2+(4-(-1))^2}\\ d=\sqrt{(-5)^2+5^2}\\ d=\sqrt{50}\\ d=\sqrt{25\cdot2}\\ d=5\sqrt2$