If $f(x)$ is an elementary function and $f(x) = g(x) + h(x)$
Does that necessarily mean that both $g(x)$ and $h(x)$ are elementary functions ?
If $f(x)$ is an elementary function and $f(x) = g(x) + h(x)$
Does that necessarily mean that both $g(x)$ and $h(x)$ are elementary functions ?
No, if $f(x)$ is the sum of an elementary function $h(x)$ with a non elementary function $g(x)$, then $f(x)+(-g(x))$ is the sum of two non elementary functions that are elementary.