Answer
$-5 + 12i$
Work Step by Step
RECALL:
(1) $(a+b)^2 = a^2+ 2ab + b^2$
(2) $i^2=-1$
Use rule (1) above with $a=2$ and $b=3i$ to obtain:
$=2^2 +2(2)(3i) + (3i)^2
\\=4 +12i + 9i^2$
Use rule (2) above to obtain:
$=4 +12i + 9(-1)
\\=4+12i+(-9)
\\=-5 + 12i$
