jika diketahui 3log5 =m dan 7log5 =n maka 35log 15 sama denga n

35log15 = 5log15 / 5log35
= 5log(5.3) / 5log(5.7)
= (5log5 + 5log3) / (5log5 + 5log7)
= (1 + 1/m) / (1 + 1/n)
= ((m+1)/m) / ((n+1)/n)
= (n.(m+1)) / (m.(n+1))

35'log 15 = 5'log 15 / 5'log 35
= (5'log 3 + 5'log 5) / (5'log 7 + 5'log 5)
= (1/m + 1) / (1/n + 1)
= ((1+m)/m) / ((1+n)/n)
= (n + nm) / (m + mn)