Bonjour,
1) 4(25)+2(1000)= 100+2000= 2 100= 2.1 x 10³
2) B= (5x10 ⁹⁺³x0.7x 10⁻⁹)/2.1= (5x0.7x 10⁶⁻⁹)⁺³/2.1= (5x0.7x1) /2.1= 3.5/2.1
≈ 1.67.
3) C= (6/4x5) x 10⁸⁺⁸⁻¹¹= 6/20 x 10¹¹= 0.3 x 10¹¹= 0.3 x 10⁵= 3 x 10⁴.
4) BxC= 1.67 x 3 x 10⁴≈ 5x10⁴.
A+C= 2.1 x 10³ + 3x10⁴= (2.1+3x10) x 10³= 32.1 x 10³= 3.21 x 10⁴.
