Answer
$-12-15i$
Work Step by Step
The given expression, $
(3i)^2-3(1+5i)
,$ is equivalent to
\begin{align*}
&
9i^2-3(1+5i)
\\&=
9i^2-3(1)-3(5i)
&\text{ (use Distributive Property)}
\\&=
9i^2-3-15i
\\&=
9(-1)-3-15i
&\text{ (use $i^2=-1$)}
\\&=
-9-3-15i
\\&=
(-9-3)-15i
&\text{ (combine like terms)}
\\&=
-12-15i
.\end{align*}
Hence, the given expression simplifies to $
-12-15i
$.
