Chapter 8 - Complex Numbers, Polar Equations, and Parametric Equations - Section 8.1 Complex Numbers - 8.1 Exercises - Page 357: 54

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

$\frac{-5+\sqrt -50}{10}=\frac{-5+\sqrt (-25\times2)}{10}=\frac{-5+5i\sqrt 2}{10}=\frac{-5}{10}+\frac{5i\sqrt 2}{10}=-\frac{1}{2}+\frac{i\sqrt 2}{2}$ We know that $\sqrt -1=i$, because $i^{2}=-1$.