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

27 log 42 =log 42/log 27 =2log(7x2x3)/2log(3x3x3)
=2log 7+2log 2+2log 3/2log 3+2log3 +2log 3
=q+1+p/p+p+p
=q+1+p/3p

 [tex] ^{27} log 42= \frac{ ^{2} log42}{ ^{2}log27 } [/tex]=
gunakan rumus[tex] ^{a} logb =\frac{ ^{c}logb }{ ^{c} loga} [/tex]
²log42=²log(2 x 3 x 7)=1+p+q
²log 27=²log3³=3.²log3=3p
[tex]^{27} log 42[/tex]=1+p+q/3p