jika 5log3=a dan 3log4=b maka 4log15=...

5 log 3 = a
3log4 = b
4log3 = 1/b


5log3 x 3log 4 = a x b
5log 4 = ab
4log4 / 4log5 = ab
4log 5 =1/ab

4log15 = 4log(5.3)
=4log 5 + 4log 3
= 1/ab + 1/b
= (1+a)/ab