Answer
$26$
Work Step by Step
RECALL:
(1) $(a+b)(a-b) = a^2-b^2$
(2) $i^2=-1$
Use rule (1) above to obtain:
$=(-5)^2 - i^2
\\=25 - i^2$
Use rule (2) above to obtain:
$=25-(-1)
\\=25+1
\\=26$
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