Question

Daca log₂ 5 = a si log ₂ 3 = b atunci log ₁₅ 12 este ?

Answer 1

$\log_{15}12=\dfrac{\log_2 15}{\log_2 12}=\dfrac{\log_2(3\cdot 5)}{\log_2 (3\cdot 4)}=\dfrac{\log_2 3+\log_2 5}{\log_2 3+ 2}=\boxed{\dfrac{a+b}{b+2}}$