Question

Dados log 2= 0,30 e log 3= 0,48.Calcule:

a) log 50 =
b) log √5 =
c) log 21 =
d) log 15 =

Answer 1

$\log50 = \log\frac{100}{2} = \log 10^2 - \log2 = 2\log10-\log2 = 2*1-0,3 = 1,7 \\ \\ \log \sqrt{5} = \log5^{\frac{1}{2}} = \frac{1}{2}*\log\frac{10}{2} = \frac{1}{2}*(\log10 - \log2) = \frac{1}{2}*(1-0,3) = \\ 0,35 \\ \\ \log21 = \log(3*7) = \log3 + \log7 = 0,48 - \log7 \\ \\ \log 15 = \log(5*3) = \log(\frac{10}{2}*3) = \log10-\log2+\log3= \\1-0,3+0,48=1,18$