Réponses

2012-05-20T14:37:32+02:00

1) -9 < 3x < 21

-21 < -3x < 9

 

2) -6 < 2x < 14

1 < 2x+7 < 21

 

3) -6/5 < 2x/5 < 7/5

-21/5 < 2x/5 - 3 < -8/5

 

FIN