Folosesti formula: [tex] log_{a}(b) = \frac{ log_{x}(b)}{ log_{x}(a)} [/tex]
[tex]a= log_{15} (12) \\ b = log_{2}(3) \\ \\ log_{15}(12) = \frac{log_{2}(12)}{ log_{2}(15) } = \frac{log_{2}(4*3)}{ log_{2}(3*5) }=\\ = \frac{ log_{2}(4)+ log_{2}(3) }{ log_{2}(5) + log_{2}(3) } = \frac{2+b}{a+b} [/tex]
