Find two functions $f,g:\Bbb R\to \Bbb R$ that are not constant such that their composition is constant?
Any help, please. Can these functions be found?
EDIT: I try next, let $f:\Bbb R\to\Bbb R$ define $f(x)=1$ if $x\in\Bbb Q$ and $f(x)=-1$ if $x\in\Bbb R-\Bbb Q$ and $g:\Bbb R\to\Bbb R$ define by $g(x)=|x|$. Then $g\circ f=1$. Is good my try?