Answer
$288i$
Work Step by Step
The given expression, $
(8i)(4i)(-9i)
,$ simplifies to
\begin{align*}
&
(8i\cdot4i)(-9i)
\\&=
(32i^2)(-9i)
\\&=
(32\cdot(-1))(-9i)
&\text{ (use $i^2=-1$)}
\\&=
-32(-9i)
\\&=
288i
.\end{align*}
Hence, the simplified form of the given expression is $
288i
$.
