Let \(f_i:[0,1]\to \mathbb R\) be a sequence of functions that converge pointwise to \(f_\infty \).
(a) Show that if the \(f_i\) are uniformly bounded then \[ \lim _{i\to \infty }\int f_i\,d\lambda =\int f_\infty \,d\lambda . \]
(b) What if \(\lVert f_i\rVert _1\le 1\) for all \(i\)?
(c) What if \(\lVert f_i\rVert _2\le 1\) for all \(i\)?