Question 1015a

Definite Integrals: Areas and Volumes

Question

(i)
Given that f{f} is a continuous function, explain, with the aid of a sketch, why the value of
lim⁡n→∞1n{f(1n)+f(2n)+⋯+f(nn)} \lim_{n \to \infty} \frac{1}{n} \left\{ f \left( \frac{1}{n} \right) + f \left( \frac{2}{n} \right) + \cdots + f \left( \frac{n}{n} \right) \right\}
is ∫01f(x)  dx.{\displaystyle \int_0^1 f(x) \; \mathrm{d}x.}
[2]
(ii)
Hence evaluate
lim⁡n→∞1n(e1n+e2n+⋯+enn).\lim_{n\to\infty} \frac{1}{n} \left( \mathrm{e}^{\frac{1}{n}}+\mathrm{e}^{\frac{2}{n}}+\cdots+\mathrm{e}^{\frac{n}{n}} \right).
[3]

Answer