J'ai un devoirs maison sur les equation pour mardi et j'ai besoin d'aide.. Merci d'acance

- 7x + 3 = 3x +12
- 4x + 8 = 2x +12
- 7x - 2 = 11 - 2x
- 13x + 8 = 9 - 6x
- (2x - 4) (7 - 3x) = 0
- (x - 3) (7x - 8) = 0

1

Réponses

2014-01-26T17:37:23+01:00
1) - 7x + 3 = 3x +12
-10x = 9
x = -9/10
2) - 4x + 8 = 2x +12
-6x = 4
x = -4/6
x = -2/3
3) - 7x - 2 = 11 - 2x
- 5x =13
x = - 13/5
4) - 13x + 8 = 9 - 6x
-7 x = 1
x = -1/7
5) - (2x - 4) (7 - 3x) = 0
(-2x + 4) (7 -3x) = 0
2 solutions possibles :
-2x +4 =0, alors x = 4/2 ⇒x =2 ou
7 - 3x = 0, alors x = -7/3
6) - (x - 3) (7x - 8) = 0
(-x + 3) ( 7x -8) = 0
2 solutions possibles :
-x +3 = 0 ⇒x= -3 ou
7x - 8 =0 ⇒ x= 8/7