5 log 3 = a , 2 log 5 = b , maka 40 log 15 = ...

Logaritma

[tex] ^5 \log 3 = a \\
^2 \log 5 = b \ \rightarrow \ ^5 \log 2 = \frac{1}{b} \\
\\
^{40} \log 15 = \frac{^5 \log 15}{^5 \log 40} \\
= \frac{^5 \log 3 \times 5}{^5 \log 2^3 \times 5} \\
= \frac{^5 \log 3 + ^5 \log 5}{3 \cdot \ ^5 \log 2 + ^5 \log 5} \\
= \frac{a + 1}{ \frac{3}{b} + 1} \ [\times \ b] \\
= \frac{b(a + 1)}{3 + b} [/tex]