Question

qual resolução deste sistema x-y=3 x-3y=11

Answer 1

$\left \{ {{x-y=3} \atop {x-3y=11}} \right. \left \{ {{x=3 + y} \atop {x-3y=11}} \right. \\\\ 3+y - 3y = 11 \\\\ -2y = 11 -3 (-1) \\\\ 2y = 8\\\\ y = 4$

Answer 2

x-y=3
x-3y= 11

1º) x-y=3
x= 3+y

2º)x-3y= 11
3+y-3y= 11
y-3y= 11-3
-2y= 8 (-1)
+2y= -8
y= -8/2
y= -4

Votando a primeira para achar valor de x.
x= 3+y
x= 3+(-4)
x= 3-4
x= -1

x= -1 e y= -4