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

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Answer 1 · 2015-02-19T16:16:17

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.