Answer
(a) $-14$
(b) $19+17i$
Work Step by Step
(a) $\sqrt {-16}-2(7+2i)=\sqrt {16(-1)}-2(7)-2(2i)=\sqrt {16}\sqrt {-1}-14-4i=4i-14-4i=-14$
(b) $(5-i)(3+4i)=5(3)+5(4i)-i(3)-i(4i)=15+20i-3i-4i^2=15+17i+4=19+17i$
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