hey guys,
my lecturer skipped the proof to show that is a generating function of the polynomials,
he told us that we should do it as an exercise by first finding the binomial series of
then insert s = -u^{2} + 2xu
he then said to expand out s^{n} and group together all the u^{n} terms,
this is what i've been doing for a while and i haven't been able to see the end,
is my approach incorrect?