jika 7log2=a dan 2log3=b, maka 12log28=

^12log28 misal ubah basis pada basis 2
= ²log28//²log12
= ²log(2².7)/²log(2².3)
= (²log2² + ²log7)/(²log2² + ²log3)
= (2 + 1/^7log2)/(2 + b)
= (2 + 1/a)/(2 + b)
= ((2a + 1)/a) / (2 + b)
= (2a + 1) / (a(2 + b))