Réponses

  • Omnes
  • Modérateur confirmé
2014-02-20T19:52:21+01:00
Salut,

a)

3a - 11 = a + 15
3a - a = 15 + 11
2a = 26
a = 26/2
a = 13

b)

2-4b = -3b - 5
-4b + 3b = -5-2
-b = - 7
b = 7

c)

-5a - 3 = a - 15
-5a - a = -15 + 3
-6a = -12
a = -12/-6
a = 2

d)
7x - 5 = -3x + 2
7x + 3x = 2 + 5
10x = 7
x = 7/10

e)

5x + 6 = 3x + 6
5x - 3x = 6-6
2x = 0
x = 0/2
x = 0

f)

3x - 5 = 3x + 7
3x - 3x = 7-2
0 = 5

cette dernière équation n'a pas de solution.
2014-02-20T20:08:19+01:00
Equation signifie égalité. Il faut regrouper les termes et trouver la valeur de x.
Exercice n° 32
3a -11 = a +15
3a -a = 11 +15
2a = 26
a = 26/2 = 13

2 -4b = -3b -5
-4b +3b = -2 -5
-b = -7
b = +7

-5a -3 = a -15
-5a -a = +3 -15
-6a = -12
a = 12/6 = 2 en positif

7x -5 = -3x +2
7x +3x = +5 +2
10 x = 7
x = 7/10

5x +6 = 3x +6
5x -3x = -6 +6
2x =0
x = 0

3x -5 = 3x +7
3x -3x = +5 +7


Exercice 33

7x +11 = 4x +15
7x -4x = -11 +15
3x = 4
x = 4/3

9x -2 = 2x -7
9x -2x = +2 -7
7x = -5
x = -5/7

-3 = x -5
-3 +5 = -x
+2 = -x
x = -2

5 -7x = -3x +2
-7x +3x = -5 +2
-4x = -3
x = +3/4

Exercice 34

5x = 0
x=0

5 +x = 0
x = 0

5 -x = 0
x = 0

5x = 1
x = 1/5

5 +x = 1
x = -5 +1
x = -4

5 -x = 1
-x = -5 +1
-x = -4
x = 4