Re: Can we find the function?

In article <1193840751.971164.78850@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
polymedes <polymedes@xxxxxxxxx> wrote:

On Oct 31, 2:44 pm, David W. Cantrell <DWCantr...@xxxxxxxxxxx> wrote:
polymedes <polyme...@xxxxxxxxx> wrote:
On Oct 31, 1:55 pm, David W. Cantrell <DWCantr...@xxxxxxxxxxx> wrote:
polymedes <polyme...@xxxxxxxxx> wrote:
Let (f o f)(x) = -2x + 3

Can we find the original function f ?

How about f(x) = Sqrt(-2) x + 1 - Sqrt(-2) ?

(Of course, I'm not saying that is the only such function.)

David

Can we answer this question instead: Is it possible for the
composition of two non-polynomial functions, to be a polynomial
function?

Sure: log(exp(x)) = x.

David

Ok, you're right, but let me change my question. Can the composition
of a non-polynomial function with itself be a polynomial, excluding
monomials?


f(x) = x^sqrt(2), f(f(x)) = ?

--
G. A. Edgar http://www.math.ohio-state.edu/~edgar/
.

Relevant Pages