Chapter 8 - Complex Numbers, Polar Equations, and Parametric Equations - Section 8.2 Trigonometric (Polar) Form of Complex Numbers - 8.2 Exercises - Page 370: 18

The sum is $-2 + 2i$. See Graph I, the resultant $-2 + 2i$ is in RED.

The sum of $2 + 3i$ and $-4 - i$ is $-2 + 2i$. Refer to Graph I, the complex number, $2 + 3i$ and $-4 - i$ are in BLUE, while the resultant $-2 + 2i$ is in RED.