(3ème /brevet) On peut m’aidez pour l’exo 6 svp c’est type brevet j’y arrive pas Merci à celui ou celle qui m’aide

T = (10^-8 ×0,7× 10¹²) ÷ (21×10³)

= [ 10^-8 × 0,7 × 10^(12-3) ] ÷ (21×10³)

= ( 10^-8 × 0,7 × 10⁹) ÷ 21

= ( 10^-8 × 7/10 × 10⁹) ÷ 21

= [10^-8 × (7× 10^-1) ×10⁹] ÷ 21

= ( 10^-8 × 7 × 10⁸) ÷ 21

= (10^-8 × 10⁸) × 7/21

= 10⁰ × 1/3

= 1 × 1/3

par suite:

T = 1/3

U = ( 3×10⁷×3,5) ÷ (21×10³)

= (10⁷÷10³) × [(3×3,5) ÷21]

= (10⁴×3×3,5) ÷ 21

= 3/21 × (10⁴×3,5)

= 1/7 × (10⁴×3,5)

= (10⁴×3,5) ÷ 7

= (10⁴ × 7/2) ÷ 7

= 10⁴/2

= 10000÷2

= 5000

alors:

U = 5000

V = 4/12 × [ [(10^-2)³×10²] ÷ 10^-3 ]

= 1/3 × [ [(10^-6 × 10²] ÷ 10^-3 ]

= 1/3 × [ 10^-4 ÷ 10^-3]

= 1/3 × 10^(-4-(-3))

= 1/3 × 10^-1

= 1/3 × 1/10

= 1/30

d'où :

V = 1/30