I would welcome further discussion on this, because unlike answer #1,
I think that the equation has no solutions rather than an infinite number of solutions.
Suppose that the integer part of r is n, and the decimal part of r is d.
That is,
\(\displaystyle r = n+d \quad \text{where}\quad n \quad \text{is an integer and}\quad 0 \leq d \leq 1. \)
Then,
\(\displaystyle \lfloor r \rfloor = n\)
so
\(\displaystyle \lfloor r \rfloor +r = 2n+d.\)
If this is to equal 15.5 then does it not imply that 2n = 15, and d = 0.5 ?
If that's the case then n = 7.5 which is a contradiction since n is an integer, so, no solution.
If the integer part of the rhs were even though, there would be a (unique) solution.
If, for example
\(\displaystyle \lfloor r \rfloor +r = 16.5, \quad \text{then} \quad r=8.5.\)
Input from someone who's used to dealing with this sort of stuff would be useful.
!
