grandes-ecoles 2018 Q6

grandes-ecoles · France · centrale-maths2__pc Sequences and Series Estimation or Bounding of a Sum
Using the result of Q5, deduce that for all $x \in \mathcal{D}_{\zeta}$, $$1 + \frac{1}{(x-1)2^{x-1}} \leqslant \zeta(x) \leqslant 1 + \frac{1}{x-1}$$
Using the result of Q5, deduce that for all $x \in \mathcal{D}_{\zeta}$,
$$1 + \frac{1}{(x-1)2^{x-1}} \leqslant \zeta(x) \leqslant 1 + \frac{1}{x-1}$$