For general loga b, where a is called the base and b is called the real number.

Domain:

Both radix and real number must be greater than zero. For example, y=log2 (small 2)(x-3) is defined as x-3 >; 0, namely x> three.

Monotonicity of functions:

For logarithmic function y=loga x, if base a >；; 1, this function is added in the domain, if the base A.

The general symbol of logarithm is log, for example, log 2 3 (2 is the base and 3 is the real number).

Lg is a special symbol, which represents the logarithm with the base of 10. When lg is used, the base of 10 does not need to be marked. For example, lg 5 represents the base of 10, and 5 is the logarithm of a real number, but the base of 10 does not need to be marked. Different from a log.

There is also a special logarithmic symbol ln, which represents the logarithm with e as the base. The use method is the same as lg, and there is no need to represent the base. For example, ln 5 means that e is the base and 5 is the logarithm of a real number.

Algorithm:

lga+lgb=lg(ab)

lga-lgb=lg(a/b)

algb=lg(b^a)