Question

${4 \cos }^{2}45 - 6 \sin30$
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Answer 1

$4Cos^{2}45^{0}-6Sin30^{0}=4*(\frac{1}{\sqrt{2}})^{2}-6*\frac{1}{2}=4*\frac{1}{2}-3=2-3=\boxed{-1}$