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Evaluate the following limit:

[tex]\[ \lim_{n \rightarrow \infty} \left(\frac{1}{n^2} + \frac{2}{n^2} + \frac{3}{n^2} + \ldots + \frac{n}{n^2}\right) \][/tex]


Sagot :

To solve the limit [tex]\(\lim_{n \to \infty}\left(\frac{1}{n^2} + \frac{2}{n^2} + \frac{3}{n^2} + \ldots + \frac{n}{n^2}\right)\)[/tex], let's first rewrite the expression in a more concise form. The limit can be expressed as:

[tex]\[ \lim_{n \to \infty} \sum_{i=1}^{n} \frac{i}{n^2} \][/tex]

We can factor out [tex]\( \frac{1}{n^2} \)[/tex] from the sum:

[tex]\[ \lim_{n \to \infty} \frac{1}{n^2} \sum_{i=1}^{n} i \][/tex]

Next, we need to find the sum of the first [tex]\( n \)[/tex] natural numbers. The formula for the sum of the first [tex]\( n \)[/tex] natural numbers is:

[tex]\[ \sum_{i=1}^{n} i = \frac{n(n+1)}{2} \][/tex]

Substituting this result into our limit expression gives us:

[tex]\[ \lim_{n \to \infty} \frac{1}{n^2} \cdot \frac{n(n+1)}{2} \][/tex]

Simplify the expression inside the limit:

[tex]\[ \lim_{n \to \infty} \frac{n(n+1)}{2n^2} = \lim_{n \to \infty} \frac{n^2 + n}{2n^2} = \lim_{n \to \infty} \frac{n^2}{2n^2} + \lim_{n \to \infty} \frac{n}{2n^2} \][/tex]

[tex]\[ = \lim_{n \to \infty} \frac{1}{2} + \lim_{n \to \infty} \frac{1}{2n} \][/tex]

As [tex]\( n \)[/tex] approaches infinity, [tex]\(\frac{1}{2n} \)[/tex] approaches [tex]\( 0 \)[/tex]:

[tex]\[ \frac{1}{2} + 0 = \frac{1}{2} \][/tex]

Hence, the limit is:

[tex]\[ \boxed{\frac{1}{2}} \][/tex]