Réponses

  • carys
  • Modératrice confirmée
2013-03-12T17:28:45+01:00

{3X-5Y=5
{4X+7Y=-7

 

 

 {12X-20Y=20
{12X+21Y=-21  

 

12X - 20Y - (12X+21Y) = 20 - (-21)

12X - 20Y -12X - 21Y = 41

-41Y = 41

Y = -1  

 

3X-5Y=5

3X-5*(-1)= 5

3X + 5 = 5

3X = 0

x = 0  

 

voilà :)

2013-03-12T17:52:45+01:00

{3X - 5Y= 5
{4X + 7Y= -7

 

-4{3X - 5Y= 5

3{4X + 7Y= -7

 

+20y +21y = -20 -21

41y = -41

y = -41/41

y = -1

 

7{3X - 5Y = 5
5{4X + 7Y = -7

 

21x +20x = 35 - 35

41x = 0

x = 0/41

x = 0