# `sum_(n=1)^oo n^2/(n^2+1)` Verify that the infinite series diverges

`sum_(n=1)^oo n^2/(n^2+1)`

To verify if the series diverges, apply the nth-Term Test for Divergence.

It states that if the limit of `a_n` is not zero, or does not exist, then the sum diverges.

`lim_(n->oo) a_n != 0`      or      `lim_(n->oo) = DNE`

`:.` `sum` `a_n` diverges

Applying this, the limit of the term of the series as n approaches infinity is:

`lim_(n->oo) a_n`

`=lim_(n->oo) n^2/(n^2+1)`

`= lim_(n->oo) n^2/(n^2(1+1/n^2))`

`=lim_(n->oo)1/(1+1/n^2)`

`=1/1+0`

`=1`

The limit of the series is not zero. Therefore, by the nth-Term Test for Divergence, the series diverges.

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