Question

Найдите log5 iz 98 ?
Lg2=a
Lg7=b

Answer 1

$\displaystyle \log_598=\frac{\lg98}{\lg5}=\frac{\lg(2\cdot49)}{\lg5}=\frac{\lg2+\lg\overbrace{49}^{7^2}}{\lg5}=\frac{\lg2+2\lg7}{\lg5}=\dfrac{a+2b}{\lg5}$