8

How to compute the limit $\lim_{n \to \infty} (1 + 2^n + 3^n +4^n+5^n)^{1/n}$?

My partial solution: $(1 + 2^n + 3^n +4^n+5^n)^{1/n} \leq (5 \times 5^n)^{1/n}$. Therefore $\lim_{n \to \infty} (1 + 2^n + 3^n +4^n+5^n)^{1/n} \leq \lim_{n \to \infty} 5^{(n+1)/n} = 5$.

Thank you very much.

LJR
  • 14,520

1 Answers1

4

HINT: $$5^n\le 1+2^n+3^n+4^n+5^n$$

Bumblebee
  • 18,220
  • 5
  • 47
  • 87