#### Answer

$-\frac{3}{8}+i\frac{\sqrt 7}{16}$

#### Work Step by Step

Take the negative out of the square root by creating an imaginary number outside it. Then simplify the square root and separate the addends into two separate fractions. Then simplify each fraction further.
$\frac{-12+\sqrt {-28}}{32}$
$\frac{-12+i\sqrt {28}}{32}$
$\frac{-12+2i\sqrt {7}}{32}$
$\frac{-12}{32}+\frac{2i\sqrt 7}{32}$
$-\frac{3}{8}+i\frac{\sqrt 7}{16}$