It should be and I don't really know how to answer your question. Is this out of a book, looking for something specific or just you pondering?
You don't have to define exp(x) as the inverse of log(x) which you defined through an integral. That's certainly possible (and is often done) but is not of any use here since we can just as well start by defining exp(x) (and after that define log(x) as its inverse, though that's not necessary here).
What the topic starter was asking, I think, is to prove the equivalence between these two possible definitions. Of course, this follows trivially from the equivalence of the analogous definition for exp(x), but proving that equivalence would be a bit 'overkill' to prove this one.
I never met two mathematicians from Analysis that define some function the same way. Every person has his own way, everything else is biconditional. I just happen to like the the integral defintion, because it demonstrates the importance of the fact that countinous functions are Riemann integrable.Originally Posted by TD!
That's a bit strange, there aren't too many ways on how log(x) and exp(x) are conventionally defined. I know at least 3 books (and thus authors, i.c. professors) who start by defining log(x) as that integral; then defining exp(x) as its inverse (which is why I remarked that it is often done ).
One of them being "my professor" (the one I had for analysis); on the other hand you have for example Rudin (from 'Principles of Mathematical Analysis') who defines exp(x) first, as the series.
There are indeed different possibilities, but fundamentally there aren't too many different definitions in use (log through the integral, the series, the limit, the initial value probem y' = y with y(0) = 1).
I see, that's true of course although I still think you'll find that many functions are often defined in a similar way - within the rather limited number of fundamentally different ways of defining them of course.
Apart from that, I just read the original question carefully. What are you exactly looking for? As said before, both expressions are completely equivalent which means, in this case, that they're the same - being e as you said already. You can prove this, but is that what you're looking for?
I couldn't tell you exactly what I'm looking for. My calculus teacher mentioned it might be part of a bonus question on a test, but wanted us to do figure it out. After looking but not really finding anything, I figured I'd ask here.
Thanks for your replies!