Respostas
Resposta:
a) x = 3 y = -1
b x = -22 y = - 2
9 9
c) x = 64 y = -45
17 17
d) x = 2 y = -3
Explicação passo-a-passo:
a) 2x + y = 5
x - y = 4
x = y +4
2( y +4) + y = 5
2y + 8 +y = 5
3y = 5 - 8
3y = -3
y = -3
3
y = -1
x = y + 4
x = -1 + 4
x = 3
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b) 2x + 5 y = -6
x - 2y = -2
x - 2y = -2
x = -2 + 2y
2( - 2 + 2y ) + 5y = -6
-4 + 4y + 5y = -6
9y = -6 + 4
9y = -2
y = - 2
9
x = -2 + 2 ( -2/9)
x = -2 - 4
9
x = -18-4
9
x = -22
9
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c) 3x +2y = -4
4x - 3y = 23
4x = 23+ 3y
x = 23 + 3y
4
3 ( 23 + 3y) + 2y = -4
4
(29 + 9 y )+ 2 y = -4 → ( x4)
4
29 + 9 y + 8y = -16
29+ 17y = -16
17y = -16 -29
y = -45
17
x = 23 + 3y
4
x = 23 + 3.(-45/17)
4
x = 23 -( 135/17)
4
x = 391 - 135
17
4
x = 256 × 1
17 4
x = 256
68
x = 64
17
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d) 2x - y = 7
x + 3y = -7
x = -7 -3y
2( -7 -3y) - y =7
-14 - 6y - y = 7
-7y = 7 +14
-7y = 21
y = -21
7
y = -3
x = -7 -3y
x = -7 - 3( -3)
x = -7 + 9
x = 2