Réponse :
29.
1. a. 3 - [12x(-5)] = 3 - (-60) = 63
b. - 7 - [14x(-5)] = -7 - (-70) = 63
30.
6a - 4 = - 1
6a = 3
a = 3/6 = 1/2 = 0,5
9a + 6 = 13a + 14
9a - 13a = 14 - 6
- 4a = 8
a = -8/4 = -2
5 - 3a = 4a - 2
-3a - 4a = - 2 - 5
- 7a = - 7
a = 1
7a = 63
a = 63/7 = 9
4a + 9 = - 39
4a = - 39 - 9
4a = - 48
a = - 48/5 = - 12
31.
a. 6(3,5) + 3 = 4(3,5) - 3
21 + 3 = 14 - 3
24 = 11 NON
b. 6(-3) + 3 = 4(-3) -3
-18 + 3 = -12 - 3
-15 = -15 OUI
c. (6x0) + 3 = (4x0) - 3
0 + 3 = 0 - 3
3 = -3 non
32.
a. 2x = x + 1/2
2x - x = 1/2
x = 1/2 oui
b. 4t² = 4
t² = 4/4 = 1
t = 1 non
c. 3a + 1 = - 5a + 5
3a + 5a = 5 - 1
8a = 4
a = 4/8 = 2/4 = 1/2 oui
33.
Nadia
9 + 2x = - 15 - 4x
2x + 4x = - 15 - 9
6x = -24
x = - 24/6 = -4 oui
Gabriel
15 - 3t = - 1 + t
- 3t - t = - 1 - 15
- 4t = - 16
t = 16/4 = 4 non
34.
1. 3 + 13b = 8b - 7
13b - 8b = - 7 - 3
5b = - 10
b = - 2 oui
2. 16a - 20 = 26a
16a - 26a = 20
- 10a = 20
a = - 2 oui
3. 5,5x = 4x + 8
5,5x - 4x = 8
9,5x = 8
x = 8/9,5 non
4. 12,5y + 4 = 3y - 15
12,5y - 3y = - 15 - 4
15,5y = - 19
y = -19/15,5 non
5. 3x² - 6x - 24 = 0
3(-2)² - 6(-2) - 24 = 0
3(4) + 12 - 24 = 0
12 + 12 - 24 = 0 oui
6. 7/2t - 1 = 1/4t + 3 7/2(-2) - 1 = 1/4(-2) + 3
7/2t - 1/4t = 3 + 1 14/2 - 1 = 1/2 + 3
14/2t - 1/4t = 4 7 - 1 = 3,5
13/2t = 4 6 = 3,5 non
13/2(-2) = 4
- 26/2 = 4
-13 = 4 non
4.
5.
6.
Explications étape par étape
