Respostas

  • Usuário do Brainly
2015-05-17T10:18:21-03:00
X + y = 20
x - y = 8
__________
2x = 28
x = 28/2
x = 14

x + y = 20
14 + y = 20
y = 20 - 14
y = 6

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3x - y = 10
x + y = 10
____________
4x = 20
x = 20/4
x = 5

x + y = 10
5 + y = 10
y = 10 - 5
y = 5

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x + 2y = 4 (*-2)
2x - 3y = 1
___________
-2x - 4y = -8
2x - 3y = 1
____________
-7y = -7
y = 7/7
y = 1

2x - 3y = 1
2x - 3(1) = 1
2x - 3 = 1
2x = 1 + 3
2x = 4
x = 4/2
x = 2
1 5 1