Question

1/3+1/15+1/35+.+1/323=9/19,

Answer 1

1/n(n+2)=1/2 *[1/n-1/(n+2)]

323=17*19

1/3+1/15+1/35+.+1/323

=1/2 [1-1/3+1/3+1/5+.+1/17-1/19]

=1/2 (1-1/19)

=9/19