Answer
$\frac{7}{4}i$
Work Step by Step
The number $i$ is defined as $\sqrt {-1}$
We use the rules of multiplication for square roots to separate the radical: $\sqrt {-1}\sqrt {\frac{49}{16}}$
We subsititute in $i$ for $\sqrt {-1}$: $i\sqrt {\frac{49}{16}}$
We simplify the real square root: $\frac{\sqrt {49}}{\sqrt {16}}i=\frac{7}{4}i$
