Réponses

2014-04-16T12:59:42+02:00
D'une manière générale :  x^{n} \times x^{m} =  x^{n+m} et  (x^{n})^{m} = x^{n\times m}

a. 10⁻¹ + 10⁴ = 1 + 10 000 = 10 001 = 1,0001 x 10⁴
b. 2 x 10⁴ x 9 x 10⁻⁹ = 18 x 10⁴⁻⁹ = 18 x 10⁻⁵ = 1,8 x 10⁻⁴
c. 6 x 10¹⁸ - 5 x 10¹⁶ = 10¹⁶(6 x 10² - 5) = 10¹⁶(600-5) =595 x 10¹⁶ = 5,95 x 10¹⁸
d. 7 x (10⁻³)² + 25 x 10⁻⁸ = 7 x 10⁻⁶ + 25 x 10⁻⁸ = 10⁻⁶(7 + 25 x 10⁻²) = 10⁻⁶(7 + 0,25) = 7,25 x 10⁻⁶