求下列极限：
.
求下列极限：.
+dfrac (1)(sqrt {{n)^2+n}})= __
+dfrac (1)(sqrt {{n)^2+n}})=1
-|||-+dfrac (1)({n)^2+n})
求极限lim_(ntoinfty)(sqrt[n]((1^2+n^2)(2^2+n^2)...(n^2+n^2)))/(1+2+...+n).求极限$\lim_
注 类似地，求极限lim_(ntoinfty)sqrt[n](((1^2+n^2)(2^2+n^2)...(n^2+n^2))/(1+2+...+n))注 类似
+dfrac (n)({n)^2+n}) __
+dfrac (n)({n)^2+n})求极限
+dfrac (n)({n)^2+n})= n/+n)=- __
lim _(narrow infty )(sqrt ({n)^2+n}-n)=____________
+dfrac (1)(sqrt {{n)^2+(n)^2}})= )=______.______.