lim [n+1-√(n²+n)] as n->∞
= lim [n-√(n²+n)]+1
= lim [n-√(n²+n)][n+√(n²+n)]/[n+√(n²+n)]+1,分子有理化
= 1-lim n/[n+√(n²+n)]
= 1-lim 1/[1+√(1+1/n)]
= 1-1/[1+√(1+0)]
= 1-1/2
= 1/2
lim [n+1-√(n²+n)] as n->∞
= lim [n-√(n²+n)]+1
= lim [n-√(n²+n)][n+√(n²+n)]/[n+√(n²+n)]+1,分子有理化
= 1-lim n/[n+√(n²+n)]
= 1-lim 1/[1+√(1+1/n)]
= 1-1/[1+√(1+0)]
= 1-1/2
= 1/2