If I type $\displaystyle\lim_{n\to\infty}n\cdot \cos\left(\frac{1}{n}\right)$
in maple, it gives as output 0.
Is this correct and if so, why?
I've tried the following myself:
$\displaystyle\lim_{n\to\infty}n\cdot\cos\left(\frac{1}{n}\right)=\lim_{k\to 0}\frac{\cos k}{k}\ldots$ ?
Am I on the right track or am I doing something wrong?
Best Answer
What you tried yourself is correct. Also, note that as $n \to \infty$, then $\cos\left(\frac{1}{n}\right) \to \cos(0) = 1$. Thus, you should be getting
$$\lim_{n\to \infty}n\cos\left(\frac{1}{n}\right) = \infty \tag{1}\label{eq1A}$$
I'm not sure why Maple is giving you a limit of $0$. However, if you use a limit of $n \to 0$ instead, then since $-1 \le \cos\left(\frac{1}{n}\right) \le 1$, you would then get $0$. Perhaps you entered the limit value into Maple incorrectly?