Bonsoir,
[tex]1) \textnormal{ Soit $(u_n)$ la suite arithm\'etique de premier terme $u_0 = 5$ et de raison 2}[/tex]
[tex]\forall n \in \mathbb{N}, u_n = u_0 +n \times r \iff \boxed{u_n = 5 + 2n}[/tex]
[tex]2)\ u_{14} = u_0 + n \times r \iff u_{14} = 5 + 14 \times 2 \iff \boxed{u_{14} =33}[/tex]
[tex]3) \ $S$ \ = (n-p+1) \times \frac{u_0 + u_{14}}{2} \iff (14 - 0 + 1) \times \frac{5 + 33}{2} \iff \boxed{15 \times \frac{5 + 33}{2} = 285}[/tex]
