Answer
$11$
Work Step by Step
RECALL:
(1) $(a-b)(a+b) = a^2-b^2$
(2) $i^2=-1$
Use rule (1) above with $a=3$ and $b=i\sqrt{2}$ to obtain:
$=3^2 - (i\sqrt{2})^2
\\=9 - i^2(2)$
Use rule (2) above to obtain:
$=9 - (-1)(2)
\\=9-(-2)
\\=9+2
\\=11$
