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 $b=5i$ to obtain: $=3^2 - (5i)^2 \\=9 - 25i^2$ Use rule (2) above to obtain: $=9 - 25(-1) \\=9-(-25) \\=9+25 \\=34$
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