n·(3·n + 5)/(4·(n + 1)·(n + 2)) + 1/(n + 1·((n + 1) + 2))
= n·(3·n + 5)/(4·(n + 1)·(n + 2)) + 1/(n + (n + 3))
= n·(3·n + 5)/(4·(n + 1)·(n + 2)) + 1/(2·n + 3)
= n·(3·n + 5)·(2·n + 3)/(4·(n + 1)·(n + 2)·(2·n + 3)) + 4·(n + 1)·(n + 2)/(4·(n + 1)·(n + 2)·(2·n + 3))
= (n·(3·n + 5)·(2·n + 3) + 4·(n + 1)·(n + 2)) / (4·(n + 1)·(n + 2)·(2·n + 3))
= (6·n^3 + 23·n^2 + 27·n + 8) / (4·(n + 1)·(n + 2)·(2·n + 3))