Bonjour,
[tex]w_0=0\\
w_1=4- \dfrac{u_0}{3} =4-0=4 \ ===\ \textgreater \ \ 1 \leq w_1 \leq 4\\\\
1 \leq w_n \leq 4\ est\ vraie\\
===\textgreater\ -\dfrac{1}{3} \geq -\dfrac{w_n}{3} \geq - \dfrac{4}{3} \\
===\textgreater\ 4- \dfrac{1}{3} \geq 4-\dfrac{w_n}{3} \geq 4- \dfrac{4}{3}\\
===\textgreater\ \dfrac{11}{3} \geq 4-\dfrac{w_n}{3} \geq 4- \dfrac{4}{3}\\
===\textgreater\ 4+\dfrac{1}{3} \geq 4 \geq w_{n+1} \geq \dfrac{8}{3} \geq 1\\\\
[/tex]
