Question

Найдите log5 iz 98 ?
Lg2=a
Lg7=b

Answer 1

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