besoin d'aide svp ?!

(3x10^-4x1.5x10^-4)/10^-6x9 = 4.5x10^-8/9x10^-6 = 0.5 x 10^-2 = 5 x 10^-3

(3x10^5-6x10^3)/3x10^11=(300 000- 6000)/3x10^11=2.94x10^5/3x10^11=9.8x10^-7

(3x10^-4x1.5x10^-4) / 10^-6x9 = 4.5x10^-8 / 9x10^-6 = 0.5 x 10^-2 = 5 x 10^-3 (3x10^5-6x10^3) / 3x10^11=(300000-6000) / 3x10^11 = 2.94x10^5 / 3x10^11 = 9.8x10^-7