Réponse :
EX1
1) U10 = 2 + 4*10 = 42
2) U8 = 5 - 2(8 - 1) = - 9
3) a = U8 - U7 = 82 - 79 = 3
4) U0+10a = 4
U0+35a = 54
....................................
-25 a = - 50 ⇔ a = 50/25 = 2
5) Un = 1/8) x 2ⁿ = 2ⁿ/2³ = 2ⁿ⁻³
U10 = 2¹⁰⁻³ = 2⁷ = 128
6) b = U1/U0 = 4/1/2 = 8
7) U1 = bU0 = b
U2 = bU1 = b x b = b² = 9 ⇔ b = - 3 ou b = 3
8) U10 = (- 2)¹⁰ = 1024
EX2
a) an = 3 n - 2 a0 = - 2 et r = 3
b) bn = (2 n + 3)/4 ; b0 = 3/4 et r = 1/2
c) cn = (n+1)²-n² = 2 n + 1 ; c0 = 1 et r = 2
Explications étape par étape :
