Question

Resolva o sistema : 2x+2y = 4 3x+y= - 1

Answer 1

  
  
  2x+2y = 4
  3x+y= - 1(-2)
 
   2x+2y = 4 
  -6x -2y=  2
     -4x = 6(-1)
        x = - 6/4
 

 2y = 4 - 2x ==> 2y = 4 - 2(-6/4) ==> 2y=4+3==> 2y=7 ==> y = 7/2

Answer 2

2x+2y=4
3x+y=-1 ⇒ y=-1-3x⇒y=-1-3(-3/2)=-1+9/2=7/2

2x+2(-1-3x)=4
2x-2-6x=4
-4x=6
x=-3/2