Given the sequences (u_n )_(n∈N) and (v_n )_(n∈N) defined
by u_n =Σ_(k=0) ^n (1/(k!)) and v_n =u_n +(1/(n(n!)))
a\ Show that (u_n )_n is of Cauchy. Deduce that
(u_n )_n converges.
b\ Show that (u_n )_n and (v_n )_n are adjacent
c\ Show that their common limit is not a rational
number.