Answer
$16 - 30i$
Work Step by Step
RECALL:
(1) $(a-b)^2 = a^2 - 2ab + b^2$
(2) $i^2=-1$
Use rule (1) above with $a=5$ and $b=3i$ to obtain:
$=5^2 - 2(5)(3i) + (3i)^2
\\=25 - 30i + 9i^2$
Use rule (2) above to obtain:
$=25 - 30i + 9(-1)
\\=25 - 30i+(-9)
\\=16 - 30i$
