grandes-ecoles 2012 QIII.A

grandes-ecoles · France · centrale-maths1__psi Sequences and Series Power Series Expansion and Radius of Convergence
In this part, $\lambda(t) = t$ for all $t \in \mathbb{R}^+$ and $f(t) = \dfrac{t}{e^t - 1} - 1 + \dfrac{t}{2}$ for all $t \in \mathbb{R}^{+*}$.
Show that $f$ extends by continuity at 0.
In this part, $\lambda(t) = t$ for all $t \in \mathbb{R}^+$ and $f(t) = \dfrac{t}{e^t - 1} - 1 + \dfrac{t}{2}$ for all $t \in \mathbb{R}^{+*}$.

Show that $f$ extends by continuity at 0.