Réponses

2013-03-10T23:15:34+01:00

1)

2x - 3y = - 14

5x = 15

x = 3

6 - 3y = -14

3y = 20

y = 20/3

 

2)

3x=y+14

3y-2x+21=0

3x - y = 14

-2x + 3y = -21

7x = 21

x = 3

9 = y + 14

y = -5

 

3)

2x+5y=3x-2y-59

7x+9y=3y-5x+78

x - 7y = 59

4x + 14y = 78

5x = 196

x = 196/5

196/5 - 7y = 59

7y = -99/5

y = -99/35