In summary, commit to memory these four basic rules of logarithms as given below:-
- Logb (mn)= logb m + logb n. In this rule, the multiplication of two logarithmic values is equal to the addition of their individual logarithms.
For example, log3 ( 2y ) = log3 (2) + log3 (y).
- Logb (m/n)= logb m – logb This is called as division rule. Here, the division of two logarithmic values is equal to the difference of each logarithm.
For example, log3 ( 2/ y ) = log3 (2) -log3 (y).
- Logb (mn) = n logb m
This is the exponential rule of logarithms. The logarithm of m with a rational exponent is equal to the exponent times its logarithm.
- Logb m = loga m/ loga b