Apabila 2log3 =a dan 5log2=b,maka 15log12 adalah…

Jawab

²log 3 = a
⁵log 2 = b

⁵log 2. ²log 3 = a b
⁵log 3 = a b

¹⁵log12= ⁵log 12 / ⁵log 15
= ⁵log 2². 3  / ⁵log 5 .3
= (⁵log 2² + ⁵log 3)/ (⁵log 5 + ⁵log 3)
= (2. ⁵log 2 + ⁵log 3) / (1 + ⁵log 3)
= (2 a + ab ) /(1 + ab)