Respostas

  • Usuário do Brainly
2013-10-16T20:14:57-03:00
A)

6x - 6y = 15
-6x + 4y = - 1
--------------
- 2y = 14 .(-1)
2y = - 14
y = -14/2
y = - 7
------------
6x - 6y = 15
6x - 6.(-7) = 15
6x + 42 = 15
6x = 15 - 42
6x = - 27
x = -27/6 (simplifique por 3)
x = - 9/2

b)

5x + 5y = 10
3x - 5y = 14
--------------
8x = 24
x = 24/8
x = 3
------------
5x + 5y = 10
5.(3) + 5y = 10
15 + 5y = 10
5y = 10 - 15
5y = - 5
y = -5/5
y = - 1