Jika ²log 3 = p dan ²log 7 = q ,maka 27log 42 adalah

 [tex] ^{27} log42= \frac{ ^{2}log42 }{ ^{2}log27 } [/tex]
=²log42=²log(2 x 3 x7)=1+p+q
=²log27=²log3³=3.²log3=3p
maka ,[tex]\frac{ ^{2}log42 }{ ^{2}log27 }= \frac{1+p+q}{3p} [/tex]

gunakan rumus=[tex] ^{a} logb= \frac{ ^{c}logb }{ ^{c}logb } [/tex]

27log42
=1/3 ³log(2.3.7)
=1/3 (³log2+³log3+³log7)

²log3=p → ³log2=1/p
²log7=q
³log2.²log7=³log7
1/p.q=q/p

1/3 (³log2+³log3+³log7)
=1/3 (1/p+1+q/p)
=1/3 {(1+p+q)/p}
= (p+q+1)/3p