Bonsoir,
Exercice 8
a) 11 = -2 + x
On passe la variable x à gauche (sans oublier de changer le signe)
-x = -11 - 2
-x = -13
x = 13
b) -4 = x +12
-x = +4 + 12
-x = 16
x = - 16
c) x - 4/3 = 1
x = + 4/3 + 1
x = 7/3
d) 3/4 + x = 5/4
x = - 3/4 + 5/4
x = 2/4
x = 1/2
e) 7/2 = x - 1
-x = - 7/2 - 1
- x = - 9/2
x = 4,5
f) - 2/5 = 4 - x
x = 2/5 + 4
x = 22/5
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Exercice 9
a) 10 = 5x
-5x = -10
x = 10/5
x = 2
b) -12 -x = -22
-x = 12 -22
-x = -10
x = 10
c) x/3 = 7
On dif=vise par le coefficient de la variable
x = 7 / (1/3)
On simplifie → x = 21
d) x + 1/2 = 1
x = -1/2 + 1
x = 1/2
e) 6/x = 3
(6 - 3x) / x = 0 → (6 - x) = 0 avec x ≠ 0
On divise par le coefficient de la variable
x = 6/3
on simplifie → x = 2
f) 1 - x = 1/3
- x = -1 + 1/3
- x = - 2/3
x = 2/3
