Réponse :

EXERCICE 1

A = 7,5 - 2,5 * 10 = 7, 5 - 25 = - 17,5

B = -3 * (2 - 9) + 0,4 * (1 - 3*7) = -3*-7 + 0,4*-2,7 = 21 - 10,8 = 10,2

C = 3 * (-6) - (- 21) : 3 = - 18 - (-7) = -18 + 7 = -11

D = -3/7 * 14/-5 = (-3*14)/(7*-5) = -42/-35 = 42/35

E = 5/9 : 1/2 = 5/9 * 2/1 = 10/9

F = 5/3 - 7 * 1/15 = 5/3 - 7/15 = (5*5)/(3*5) - 7/15 = 25/15 - 7/15 = 18/15 = (3*6)/(3*5) = 6/5

G = 7/6 -  (-1/2 + 1/3) = 7/6 - [(-1*3)/(2*3) + (1*2)/(3*2)] = 7/6 - (-3/6 + 2/6) = 7/6 - (-1/6) = 7/6 + 1/6 = 8/6 = (2*4)/(2*3) = 4/3

H = -7/4 + 1/9 : 4 = -7/4 + (1/9 * 1/4) = - 7/4 + 1/36 = (-7*9)/(4*9) + 1/36 = -63/36 + 1/36 = -62/36 = (-31*2)/(18*2) = -31/18

EXERCICE 3

1. 4 + 3 = 7 * 2 = 14 - 8 = 6

2. -5 + 3 = -2 * 2 = -4 - (-10) = 6

3. pour tout nombre x, le résultat sera le même

4. (x + 3) * 2 - x² = 6

EXERCICE 3

Explications étape par étape :