2. the domain of y = lnx is x >；; 0。
The logarithm with the base of n is recorded as
Logarithmic symbol log is derived from Latin logarithm and was first used by Italian mathematician cavalieri. At the beginning of the 20th century, the modern representation of logarithm was formed. For the convenience of use, people gradually recorded the ordinary logarithm with the base of 10 and the natural logarithm with the base of irrational number e as lgN and lnN respectively.
Extended data:
Logarithmic definition:
1, in particular, we call the logarithm with the base of 10 as the common logarithm and record it as lg.
2. Logarithm based on irrational number e (e=2.7 1828 ...) is called natural logarithm, and is recorded as ln.
3. Zero has no logarithm.
4. In the range of real numbers, negative numbers have no logarithm. In the range of imaginary numbers, negative numbers are logarithms.
Baidu encyclopedia-logarithm
Baidu encyclopedia-natural logarithm