Prove $$\sum_{n=0}^{\infty}\frac{1}{1+(x-n)^{2}}$$ converges for $x \in \mathbb{R}$.
I am having difficulty solving this using the ratio test.
Prove $$\sum_{n=0}^{\infty}\frac{1}{1+(x-n)^{2}}$$ converges for $x \in \mathbb{R}$.
I am having difficulty solving this using the ratio test.
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$$\sum_{n=0}^{\infty}\dfrac{1}{1+(x-n)^{2}} =\sum_{n=0}^{k}\dfrac{1}{1+(x-n)^{2}} +$$
$$\sum_{n=k+1}^{\infty}\dfrac{1}{1+(x-n)^{2}} $$ where $k$ is an integer larger than $x+1$.
The first sum is no problem.
The second one $$\sum_{n=k+1}^{\infty}\dfrac{1}{1+(x-n)^{2}}\le \sum_{n=1}^{\infty}\dfrac{1}{1+n^{2}}$$
Which is convergent.