Let f(x) be a function defined on [0, 1] such that f(x)={x, if x ϵ Q1−x, if x /ϵ Q Then, for all x ϵ [0,1],f(f(x))=
constant
1+x
x
none of these
If x ϵ Q,f(x)=xf{f(x)}=f(x)=xIf x /ϵ Q,f(x)=1−xf{f(x)}=f(1−x)=1−(1−x)=x⇒f{f(x)}=x ∀ x ϵ [0,1]