Evaluate limn→∞∑k=1nnn2+9k2\lim_{n \to \infty} \sum_{k=1}^n \frac{n}{n^2 + 9k^2}limn→∞∑k=1nn2+9k2n.
19arctan(3)\frac{1}{9}\arctan(3)91arctan(3)
π3\frac{\pi}{3}3π
13arctan(3)\frac{1}{3}\arctan(3)31arctan(3)
arctan(3)\arctan(3)arctan(3)