Réponses

2014-04-25T14:30:43+02:00
Résoudre ces équations :

1 - 2(3x - 4) = 5x - 2 (3x - 5)
1 - 6x + 8 = 5x - 6x + 10
1 - 6x + 8 - 5x + 6x - 10 = 0
-5x = - 1 - 8 + 10
- 5x = 1
x = -1/5 ou  x = - 0,2

-4x + 2/7 = 16/7
-4 * 7x / 1 * 7 + 2/7 = 16/7
-28x/7 + 2/7 = 16/7
-28x + 2 = 16
-28x = 16 - 2
-28x = 14
x = -14/28 ou x = - 0,5

5/4x = 2 + 1/4x
5/4x = 2 x 4 / 1 x 4 + 1/4x
5/4x = 8/4 + 1/4x
5x - x = 8
4x = 8
x = 8/4
x = 2

5 - x/7 = x - 3/3
5 * 21 / 1 * 21 - x * 3 / 7 * 3 = x * 21 / 1 * 21 -  3 * 7 / 3 * 7
105/21 - 3x/21 = 21x/21 - 21/21
105 - 3x = 21x - 21
-3x - 21x = -21 - 105
-24x = - 126
x = 126/24 ou x = 5,25

-x - 6 (- 5 - 3x) = 2 (-2x + 9) - 5

- x  + 30 + 18x = - 4x + 18 - 5
- x + 4x + 18x = - 30 + 18 - 5
21x = -17
x = -17/21 ou x = - 0,80


Meilleure réponse !
2014-04-25T14:48:58+02:00
Tu développes et réduits les expressions , tu isoles les "x" du même coté et les constantes de l'autre soit

1-2(3x-4)=5x-2(3x-5)
1-6x+8 =5x-6x +10
1-6x+6x +8 -5x  = 5x -5x -6x +6x +10
-5x+9 =10
-5x+9-9=10-9
-5x=1
(-5/-5)x=-1/5
x=-1/5

-4x+2/7=16/7

-4x+2/7-2/7=16/7-2/7
-4x+0=14/7
-4x=2
(-4/-4)x=2/-4
x=-1/2

5/4x=2+1/4x
5/4x-1/4x=2+1/4x-1/4x
4/4x=2+0
1x=2
x=2

5-x/7=x-3/3

-x/7+5-x=x-x-3/3
-x/7-x +5-5 = 0 -1 -5
-x/7 -x =-6
-x/7-7x/7 = -6
-8x/7 =-6
(-8/7)x=-6
(-7/8)(-8/7)x=-6(-7/8)
x=42/8
x=21/4

-x-6(-5-3x)=2(-2x+9)-5

-x+30+18x=-4x +18 -5
-x+18x+4x = -30 +18 -5

21x = -17
x=-17/21