Diketahui 2log 3=a dab 2log 5=b nilai 5log 30=

5log 30 = 5log 5 + 5log 6
5log 30 = 1 + 5log 2 + 5log 3
5log 2 = 1/b
5log 3 = 5log 2 x 2log 3 = 1/b x a = a/b
sehingga
5log 30 = 1 + 1/b + a/b
5log 30 = (b+1+a)/b