Question:
Write the range of the function f(x) = ex−[x], x ∈ R.
Solution:
$f(x)=e^{x-[x]}, x \in \mathrm{R}$
We know that $x-[x]=\{x\}$, which is the fractional part of any number $x$.
Thus, $f(x)=e^{\{x\}}$
Also, $0 \leq\{x\}<1$
$\Rightarrow e^{0} \leq e^{\{x\}} $\Rightarrow 1 \leq f(x) Thus range of $f(x)$ is $[1, e)$.