Réponses

2013-05-20T13:56:39+02:00

5x + 3y = 77

4x - 2y = 22

 

 

4 * (5x + 3y) = 4 * 77

5 * (4x - 2y) = 5 * 22

 

 

20x + 12y = 308

20x - 10y = 110

 

 

20x + 12y = 308

20x = 110 + 10y

 

 

On résoud l'équation : 

 

 

110 + 10y + 12y = 308

110 + 22y = 308

22y = 308 - 110

22y = 198

y = 198

      22

y = 9

 

On calcule x :

 

5x + 3y = 77

5x + 3 * 9 = 77

5x + 27 = 77

5x = 77 - 27

5x = 50

x =  50 

       5

x = 10