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Calculati: log2 (cos 60°)+log2 (sin 30°) va rog

Răspuns :

[tex]=log_{2}~\frac{1}{2}+log_{2}~\frac{1}{2}=[/tex]

[tex]=log_{2}(\frac{1}{2}*\frac{1}{2})=[/tex]

[tex]=log_{2}(\frac{1}{4})=[/tex]

[tex]=log_{2}(\frac{4}{16})[/tex]

[tex]=log_{2}4-log_{2}16[/tex]

[tex]=log_{2}2^{2}-log_{2}2^{4}[/tex]

[tex]=2*log_{2}2-4*log_{2}2[/tex]

[tex]=2*1-4*1[/tex]

[tex]=2-4=-2[/tex]
[tex]\log_{\big2}( \cos60^o) +\log_{\big2}( \sin30^o) = \\ \\ = \log_{\big2} \dfrac{1}{2}+\log_{\big2} \dfrac{1}{2} = \\ \\ = \log_{\big2}2^{-1} +\log_{\big2}2^{-1} = \\ \\ = - \log_{\big2}2 + \Big(-\log_{\big2}2\Big) = \\ \\ = -1 +(-1) = \\ \\ = -1-1 = \\ \\ =-2[/tex]