jika 2 log 3=a 3 log 5=b berapa 15 log 20???

2log3 = a
3log5 = b
2log3 × 3log5 = 2log5 = ab

15log20

15log2×2×5

15log2 + 15log2 + 15log5

1 1 1
---------- + ---------- + ----------
2log15 2log15 5log15

1 1 1
------------ + ------------ + -------------
2log3×5 2log3×5 5log3×5

1 1
-------------------+-------------------+-------------------
2log3+2log5 2log3+2log5 5log3+5log5

1 1 1
--------- + --------- + ---------
a + ab a + ab 1/b + 1

2 1
--------- + ------------
a + ab 1/b + b/b

2 1
--------- + -----------
a + ab (1 + b)/b

2 b
--------- + -------
a + ab 1 + b

2 (1 + b) + b (a + ab)
-----------------------------
(a + ab) (1 + b)

2 + 2b + ab + ab^2
----------------------------
a + ab + ab + ab^2

2 + 2b + ab + ab^2
---------------------------
a + 2ab + ab^2