7 log 3 =p dan 3 log 5 = q , maka 35 log 15 =

^35log 15 = ³log 15 / ³log 35
= ³log (5×3) / ³log (5×7)
= ³log 5 + ³log 3 / ³log 5 + ³log 7
= q+1 / q+(1/p)
kalikan p
= qp+p / qp+1