Bonsoir,
Exercice 7
E = 8/3 + 5 ÷ (1 - 2/5)
E = 8/3 + 5 ÷ (5/5 - 2/5)
E = 8/3 + 5 ÷ 3/5
E = 8/3 + 5 × 5/3
E = 8/3 + 25/3
E = 33/3
E = 11
F = (55 × 10³ × 2¹º)/(10⁴ × 2^9)
F = 55 × 10^(3 - 4) × 2^(10 - 9)
F = 55 × 10-¹ × 2¹
F = 110 × 10-¹
F = 110 × 0,1
F = 11
Donc on a E = F = 11
Exercice 8
Virus de la varicelle : 1 750 × 10^(-10) m 1,750 × 10³ × 10^(-10) = 1,750 × 10^(-7) m
Virus de la gastro entérite : 0,07 × 10^(-6) m = 7,0 × 10-² × 10^(-6) = 7,0 × 10^(-8) m
Virus de la fièvre : 40 × 10^(-9) = 4,0 × 10¹ × 10^(-9) = 4,0 × 10^(-8)
Ordre croissant :
4,0 × 10^(-8) < 7,0 × 10^(-8) < 1,750 × 10^(-7)
Exercice 9
Vitesse = Distance / Temps
Temps = Distance / Vitesse
Temps = (1,5 × 10^8)/(3 × 10^5) = 1,5/3 × 10^8/10^5 = 0,5 × 10^5 s = 1,5 × 10⁴ s
Produit en croix
60s = 1 min
1,5 × 10⁴ s = (1,5 × 10⁴) × 1/ 60 = 250 min
