bjr
1)
A = (4³ x 2⁻³) / 8⁵
on écrit 4³ et 8⁵ comme puissances de 2
4³ = (2²)³ = 2⁶ (on multiplie les exposants 2 x 3 = 6)
8⁵ = (2³)⁵ = 2¹⁵ (3 x 5 = 15)
A = (2⁶ x 2⁻³) / 2¹⁵ ( 1/2¹⁵ = 2⁻¹⁵)
A = (2⁶ x 2⁻³) x 2⁻¹⁵ (on ajoute les exposants)
A = 2⁶⁻³⁻¹⁵
A = 2⁻¹²
2)
B = 9² x 3⁻³ x 81 9² = (3²)² = 3⁴ ; 81 = 9² = 3⁴
B = 3⁴ x 3⁻³ x 3⁴
B = 3⁴⁻³⁺⁴
B = 3⁵
3)
C = (10⁻⁴ x 10¹¹) / (10³)²
C = (10⁻⁴ x 10¹¹) / 10⁶
C = 10⁻⁴ x 10¹¹ x 10⁻⁶
C = 10⁻⁴⁺¹¹⁻⁶
C = 10¹
C = 10
