calculus - summation of series by telescoping series method (feedback needed)

i am stuck i did the first part by cancelling out terms since its a telescoping series. But I do not know how I can proceed any further . Please help. I am not sure of whatever i have done so far. so Please see also for the errors.

Answer

What you have done is correct. Now it is straightforward that

$$\lim_{n \to \infty} -\ln 2 + \ln(n+2)= -\ln 2 + \lim_{n \to \infty}\ln(n+2)=+\infty$$ since $\ln$ is a monotone increasing function.

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If you need to prove that $\ln n$ is unbounded you need the following:

$$\ln' n=\dfrac{1}{n}>0$$ so that $\ln$ is monotone increasing. Moreover $\ln 2>\ln 1=0$. Now, take $M\in \mathbb R$, arbitrarily large. Then there exists $m \in \mathbb N$ such that $$M0$) or equivalently$M< \ln 2^m$. Therefore for any$n>2^m$you have that$$M<\ln 2^m <\ln n$$from which you can conclude that$\ln n$is unbounded since$M$ was arbitrarily large.