1.
Let Q\mathbb{Q} be the set of all rational numbers in [0,1][0, 1] and f:[0,1]→[0,1]f : [0, 1] \to [0, 1] be defined by f(x)={xfor x∈Q1−xfor x∉Qf(x) = \begin{cases} x & \text{for } x \in \mathbb{Q} \\ 1-x & \text{for } x \notin \mathbb{Q} \end{cases}. Then, the set S={x∈[0,1]:(f∘f)(x)=x}S = \{x \in [0, 1] : (f \circ f)(x) = x\} is equal to
Sets, Relations and Functions - Medium - Question