Answer
$\color{blue}{-3-i\sqrt{2}}$
Work Step by Step
Simplify $\sqrt{-18}$ to obtain:
$=\sqrt{9(-1)(2)}
\\=\sqrt{3^2(-1)(2)}
\\=3\sqrt{(-1)(2)}$
Since $\sqrt{-1} = i$, the expression above simplifies to:
$=3i\sqrt{2}$
Thus, the given expression is equivalent to:
$=\dfrac{-9-3i\sqrt{2}}{3}$
Divide each term of the numerator by the denominator to obtain:
$=\dfrac{-9}{3} - \dfrac{3i\sqrt{2}}{3}
\\=\color{blue}{-3-i\sqrt{2}}$
