Limit to infinity part 2

Calculus Level 4

lim n ( ( n + 1 ) 5 + ( n + 2 ) 5 + + ( n + 10 ) 5 n 4 10 n ) \lim_{n\rightarrow \infty} \left( \dfrac{ (n+1)^{5}+ (n+2)^{5}+\cdots + (n+10)^{5}}{n^{4}} - 10n \right)


The answer is 275.

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3 solutions

Daniel Ferreira
Apr 25, 2015

lim x ( n 5 + 5 n 4 + . . . ) + ( n 5 + 10 n 4 + . . . ) + . . . + ( n 5 + 50 n 4 + . . . ) 10 n 5 n 4 = lim x 10 n 5 + 275 n 4 + . . . 10 n 5 n 4 = lim x = n 4 ( 275 + p n + q n 2 + . . . ) n 4 = 275 + 0 = 275 \lim_{x \to \infty} \frac{(n^5 + 5n^4 + ...) + (n^5 + 10n^4 + ...) + ... + (n^5 + 50n^4 + ...) - 10n^5}{n^4} = \\\\\\ \lim_{x \to \infty} \frac{\cancel{10n^5} + 275n^4 + ... - \cancel{10n^5}}{n^4} = \\\\\\ \lim_{x \to \infty} = \frac{n^4(275 + \frac{p}{n} + \frac{q}{n^2} + ...)}{n^4} = \\\\ 275 + 0 = \\\\ \boxed{\boxed{275}}

Obs.: p , q N \forall \, p, q \in \mathbb{N} .

Mayank Singh
Apr 11, 2015

Just apply the binomial expansion

The above hint is more than enough

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