\(\log_8 13 = \frac{\ln 13}{\ln 8} ≈ \frac{2.565}{2.079} ≈ 1.23\)
\(\log_9 12 = \frac{\ln 12}{\ln 9} ≈ \frac{2.485}{2.197} ≈ 1.13\)
\(\log_{0.3} 8 = \frac{\ln 8}{\ln 0.3} ≈ \frac{2.079}{-1.204} ≈ -1.73\)
\(\log_{1.5} 0.78 = \frac{\ln 0.78}{\ln 1.5} ≈ \frac{-0.248}{0.405} ≈ -0.61\)
Ответ: 1) ≈ 1.23, 2) ≈ 1.13, 3) ≈ -1.73, 4) ≈ -0.61