How can I find $x$ having integer $f(x)$?
For example, when there are $f(x) = 5e^{-x}$ or $f(x) = -x + 6$ etc..., I want to find all x having integer $f(x)$.
How can I find it? It doesn't matter if it's another function.
Asked
Active
Viewed 53 times
1
-
3If you can get the function inverse, you could write $f(x)=n=5e^{-x}$, then the values are $x_n = - \log(n/5)$, for all the possible values of $n \in \mathbb{Z}$. This might run into problems for other functions, and certain values of $n$. – Benedict W. J. Irwin Aug 14 '19 at 18:25
-
It's impossible really to do this for all functions. – kingW3 Aug 14 '19 at 18:44