1-
A = 1/3 - 1/2 x (3-1/5)
A = 1/3 - 1/2 x (15/5-1/5)
A = 1/3 - 1/2 x 14/5
A = 1/3 - 14/(2x5)
A = 1/3 - 7/5
A = (5 - 3x7)/(3x5)
A = (5 - 21)/15
A = 16/15
2-
^ se lit puissance
(0.25 x 10^-2 x 3 x 10^4)/(2 x 10 x 6 x 10^2) or 10^^-2 x 10^4 = 10^(-2+4) = 10^2
= (0.25 x 10^2 x 3)/(2 x 10 x 6 x 10^2) or 10^2/10^2 = 1
= (0.25 x 3)/(2 x 10 x 6) or 0.25 = 2.5 x 10^-1 et 6 = 3x2
= (2.5 x 10^-1 x 3)/(2 x 10 x 3 x 2)
= (2.5 x 10^-1)/(2 x 10 x 2) or 1/10 = 10^-1
= (2.5 x 10^-1 x10^-1)/4
= (2.5 x 10^-2)/4
= 0.625 x 10^-2
= 6.25 x 10^-1 x 10^-2
= 0.00625 écriture décimale
= 6.25 x 10^-3 écriture scientifique
