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\lim _{n \rightarrow \infty} \frac{3}{n}\left\{4+\left(2+\frac{1}{n}\right)^{2}+\left(2+\frac{2}{n}\right)^{2}+\cdots+\left(3-\frac{1}{n}\right)^{2}\right\}  is equal to

Option: 1

12


Option: 2

\frac{19}{3}


Option: 3

0


Option: 4

19


Answers (1)

best_answer

\lim _{x \rightarrow \infty} \frac{3}{n}\left\{\underset{\substack{4 \\ \uparrow \\(2+0/n)^{2}}}{ }(2+1 / n)^{2}+\left(2+\frac{2}{n}\right)^{2}+\ldots .+\left(3-\frac{1}{n}\right)^{2}\right\}
\Rightarrow \sum_{r=0}^{n-1} \frac{3}{n}\left(2+\frac{r}{n}\right)^{2}
\Rightarrow \int_{0}^{1} 3(2+x)^{2} d x
\Rightarrow\left[(2+x)^{3}\right]_{0}^{1}
\Rightarrow(2+1)^{3}-(2+0)^{3}
\Rightarrow 27-8=19

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shivangi.bhatnagar

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