Réponse:
on utilise la relation: Un= U(0) +(n-1)r
U(1)= 0+(1-1)10
U(1)=0
U(2)= 0+(2-1)10
U(2)=10
U(3)=0+(3-1)10
U(3)=20
U(4)=0+(4-1)10
U(4)=30
U(1)= 100+(1-1)×(-3)
U(1)=100
U(2)=100+(2-1)×(-3)
U(2)=97
U(3)=100+(3-1)*(-3)
U(3)=94
U(4)=100+(4-1)*(-3)
U(4)=91