Réponses

2014-06-04T20:35:45+02:00
{5x + y=12
{4x - 3y = -17 

{y=12-5x
{4x - 3(12-5x) = -17 

{y=12-5x
{4x -36+15x = -17 

{y=12-5x
{19x/19=19/19

{y=12-5x
{x=1

{y=12-5*1
{x=1

{y=7
{x=1

voilà :)