1. ## ln and e?

I saw a final answer from a question: $\ln x=1$therefore $x=e$how they will become like this?

What is $\ln$ and $e$? Is there any formula or rule for them?

2. By definiton:

ln(x) = y means e^y = x

ln(x) = 1 then e^1 = x

another way of looking at this is that ln(x) and e^x are inverses therefore

e^(ln(x) = ln(e^x) = x

so if ln(x) = 1

e^(ln(x)) = e^1

x = e