limn→∞(1+2+…+nn+2−n/2)_．
问题描述：
(lim n→∞
−1+2+…+n n+2
)______． n 2
答
(lim n→∞
−1+2+…+n n+2
)=n 2
(lim n→∞
−
n(1+n) 2 n+2
)n 2
=
lim n→∞
=−−n 2(n+2)
1 2
故答案为：−
1 2