Diketahui 3log5=m,3log7=n,nilai 15log245 adalah…

15log245 = 3log245 / 3log15
= 3log(7²x5) / 3log(5×3)
= (3log7² + 3log5) / (3log5 + 3log3)
= (2.3log7 + 3log5) / (3log5 + 3log3)
= (2n + m) / (m + 1)

³log 5 = m
³log 7 = n

maka
¹⁵log 245
= ³log 245 / ³log 15
= ³log 5x7x7 /  ³log 3×5
= ³log 5 + ³log 7 + ³log 7 / ³log 3 + ³log 5
= m + n + n /  1 + m
= (m+2n) / (m+1)

Semoga membantu… 🙂