a) Tính $\mathop {\lim }\limits_{} \left ( \frac{1}{n+1}+\frac{1}{n+2}+..+\frac{1}{n+n}\right ) $b)
Tính $ \mathop {\lim }\limits_{} \left ( \frac{\sqrt[n]{2}
}{n+1}+\frac{\sqrt[n]{2^2} }{n+\frac{1}{2} }+...+\frac{\sqrt[n]{2^n}
}{n+\frac{1}{n} }\right ) .$