Réponse :
Ex 4
− 10 x + 23+ (− x) + 56= 5 x − 52
- 10 x + 23+ (− x) + 56 - 5 x= 5 x − 52 - 5 x
- 10 x + 23 + (− x) + 56 - 5 x -23 = − 52 - 23
- 10 x + (− x) + 56 - 5 x - 56 = - 52 - 23 - 56
- 10 x + (− x) - 5 x = -131
- 16 x = -131
Ex 5
par combinaison :
[tex]\left \{ {{-8 x + 6 y = 108} \atop {-6 x + 8 y = 102}} \right.[/tex]
[tex]\left \{ {{(-8 x * 8) + (6 y*8) = 108* 8} \atop {(-6 x*(-6)) + (8 y* (-6)) = 102* (-6)}} \right.[/tex]
[tex]\left \{ {{-64x + 48y = 864} \atop {36x - 48y = -612}} \right.[/tex]
-64x + 48y + 36x - 48y = 854 -612
-64x +36x = 252
-28x = 252
x = 252/28 = 9
−8 x + 6 y = 108
−8 × 9 + 6 y = 108
-72 +6y = 108
6y = 108 +72 = 180
y = 180/6 = 30