Question

How do you find the domain and range of a natural log?

Answer 1

Hello,

The natural logarithm, also called neperian logarithm, is noted `ln`.

The domain is `D=]0,+\infty[` because `\ln(x)` exists if and only if `x>0`.

The range is `I=RR = ]-oo,+oo[` because `ln` is strictly croissant and `\lim_{x\to-oo} ln(x) = 0` and `\lim_{x\to+oo} ln(x) = +oo`.

graph{ln(x) [-2.125, 17.875, -4.76, 5.24]}

The domain `D` is the projection of the curve of `ln` on the x axe.

The range `I` is the projection of the curve on y axe.