If $f(x)=\left\{\begin{matrix}x\,when\,x\,is\,rational\\1-x\,when\,x\,is\,irrational\end{matrix}\right.$ then fof(x) is given as
Answer & explanation
Correct answer: option 2
$fof=\left\{\begin{matrix}f(x)\,when\,f(x)\,is\,rational\\1-f(x)\,when\,f(x)\,is\,irrational\end{matrix}\right.$
$=\left\{\begin{matrix}x\,when\,f(x)\,is\,rational\\1-(1-x)\,when\,f(x)\,is\,irrational\end{matrix}\right.=x$
That is, it fof(x) = x.