2 1 2n
(------------ + -----------)•(n–5)^2+ -------- =
(5–n)^2 25–n^2 n+5
2 1
= (------------ + --------------) • (n–5)^2 +
(5–n)^2 (5–n)(5+n)
2n [2(5+n)+(5–n)]•(n–5)^2
+ ------ = -------------------------------- +
n+5 (5–n)^2•(5+n)
2n (10+2n+5–n)(n^2–10n+25)
+ ------ = ------------------------------------- +
n+5 (25–10n+n^2)(5+n)
2n 15+n 2n 15+n+2n
+ ------ = ------- + ------ = ------------- =
n+5 5+n n+5 n+5
15+3n 3(5+n)
= --------- = --------- = 3
n+5 n+5