Jika diketahui 2log 3 = x dan 3log 7 = y maka 56log 14 =...

56 log 14 = 3 log 14 / 3 log 56
=3 log 2 x 2 x 7  /  3 log 2 x 2 x 2 x 2 x  7
= 1/x + 1/x + y  / 1/x + 1/x + 1/x + 1/x + y
= 2+xy / x  / 4+xy /x
= 2+xy / 4+xy

2log 3 = log 3 / log 2 = x
3log 7 = log 7 / log 3 = y
56log 14 = log 14 / log 56
= log (7×2) / log (8×7)
= (log 7 + log 2) / (log 8 + log 7)
= (log 7 + log 2) / (log 2^3 + log 7)
= (log 7 + log 2) / (3.log 2 + log 7)
Ganti bilangan pokok logaritma menjadi 3...
= (3log 7 + 3log 2) / (3.3log 2 + 3log 7)
Jadi,
= ( y + 1/x ) / ( 3/x + y )

Semoga bermanfaat.....
-Prisco