DM A rendre demain , J'y arrive pas ! Les calculs surlignés en plus de l'ecriture decimale faut aussi donner le resultat en ecriture scientifique . aidez moi je

Bonsoir

A = 7/15 - 18/60 = 28/60 - 18/60 = 10/60 = 1/6

B = 75 x 10⁴ sur 2 x 10² = 37.5 x 10² = 3.75 x 10³

C = (2/5 + 1/4) : (2/5 - 1/4) = (8/20 + 5/20) : (8/20 - 5/20) = 13/20 : 3/20
C = 13/20 x 20/3 = 260/60 = 13/30

D = 2⁶
E = 12⁵
F = 2⁹

G = 3/7 - 42/56
G = 24/56 - 42/56 = - 18/56 = -9/ 28

H = 5.4 x 10 ⁻¹ sur 6 x 10⁴
H = 0,9 x 10⁻⁵
H = 9 x 10 x 10⁻⁵ = 9 x 10 ⁻⁴

I = (2/3 +1/2) : ( 17/9 - 1/3) = (4/6 + 3/6) : ( 51/27 - 9/27) 
I = 7/6 : 42/27 = 7/6 x 27/42 = 189/252 = 3/4

J = 486 x 10⁻⁷ sur 18 x 10⁻²
J = 27 x 10⁻⁵ = 2.7 x 10 x 10⁻⁵ = 2.7 x 10⁻⁴