求
求
+dfrac (n)({n)^2+n+n})=dfrac (1)(2)证明:
lim _(narrow infty )(dfrac (1)({n)^2+n+1}+dfrac (2)({n)^2+n+2}+... +dfrac (n)({n
+dfrac (sin n)({2)^n} ;-|||-(2) _(n)=1+dfrac (1)({2)^2}+dfrac (1)({3)^2}+... +df
+(n)^3);-|||-(2) lim _(narrow infty )n[ dfrac (1)({(n+1))^2}+dfrac (1)({(n+2))^2
+dfrac (n)({n)^2+n+n})..
+dfrac (n)({n)^2+n+n})=_____.求极限=_____.
+dfrac (n)({n)^2+n})= n/+n)=- __
+dfrac (n)({n)^2+n})求极限
+dfrac (n)({n)^2+n}) __
_(n)=((-1))^n+1dfrac (1)(sqrt {n)}-|||-C. _(n)=sin dfrac (npi )(2)-|||-D. _(n)=d