Chapter 8 - Complex Numbers, Polar Equations, and Parametric Equations - Section 8.1 Complex Numbers - 8.1 Exercises - Page 357: 53

$-\frac{1}{8}+\frac{i\sqrt 2}{8}$

$\frac{-3+\sqrt -18}{24}=\frac{-3+\sqrt (-9\times2)}{24}=\frac{-3+3i\sqrt 2}{24}=\frac{-3}{24}+\frac{3i\sqrt 2}{24}=-\frac{1}{8}+\frac{i\sqrt 2}{8}$ We know that $\sqrt -1=i$, because $i^{2}=-1$.