(3) Calculer de deux façons chaque expression: 5x (2.2 +3,8); b 9x(10,7 -6,4): 2x2,7 + 2 x 10,3: 7x13,4 - 7x11,2. SVP

5X (2.2+3.8) = 5X*6 =30X

5X(2.2+3.8) =5X*2.2+5X*3.8 = 11X+19X = 30X

9X(10.7-6.4) = 9X*4.3 = 38.7X

9X(10.7-6.4) = 9X*10.7 -9X*6.4 = 96.3X-57.6X = 38.7X

2*2.7+2*10.3 = 5.4+20.6 = 26

2*2.7+2*10.3 = 2(2.7+10.3) = 2*13 = 26

7*13.4-7*11.2 = 93.8-78.4 = 15.4

7*13.4-7*11.2 = 7(13.4-11.2) = 7*2.2 = 15.4