Jika 2log3 = a dan 3log5=b, maka 4log 15 =

4log15 = 4log3+4log5
=1/2 2log3 + 3log5/3log4 = 1/2a+b/3log4
= 1/2a+b(1/2a) = 1/2a(1+b)

4log15 = 2^2 log(3 x 5 )
1/2 x 2 log 3 + 2log 5
1/2 x a + 2 log 5

maaf kalo salah