Past exam of the mathematics course of the University of Cambridge / 2022 / ib / Paper 1 / 10G / a / Solution

This is always true. Given $\epsilon >0$, choose $N_A,N_B$ such thaton $A$ for $n\ge N_A$ and on $B$ for $n\ge N_B$. For $n\ge \max (N_A,N_B)$ the same inequality holds at every point of $X=A\cup B$. Hence $f_n\to f$ uniformly on $X$.

Solved by gpt-5.6-sol high.