Respuestas
Respuesta:
a) x=1; y=6
b) x=7; y=2
c) x=6; y=4
c) x=3; y=2
Explicación paso a paso:
a) x + y = 7
5x - 2y = -7
>> x + y = 7
x = 7 - y
>> 5x - 2y = -7
5(7 - y) - 2y = -7
35 - 5y - 2y = -7
-7y = -7 - 35
-7y = -42
y = -42 / -7
y = 6
>> x = 7 - y
x = 7 - 6
x = 1
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b) 2x + 3y = 20
x - 2y = 3
>> x - 2y = 3
x = 3 + 2y
>> 2x + 3y = 20
2(3 + 2y) + 3y = 20
6 + 4y + 3y = 20
7y = 20 - 6
7y = 14
y = 14 / 7
y = 2
>> x = 3 + 2y
x = 3 + 2(2)
x = 3 + 4
x = 7
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c) x + y = 10
x - y = 2
>> x - y = 2
x = 2 + y
>> x + y = 10
2 + y + y = 10
2y = 10 - 2
2y = 8
y = 8 / 2
y = 4
>> x = 2 + y
x = 2 + 4
x = 6
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d) x + 3y = 9
5x - 2y = 11
>> x + 3y = 9
x = 9 - 3y
>> 5x - 2y = 11
5(9 - 3y) - 2y = 11
45 - 15y - 2y = 11
45 - 17y = 11
- 17y = 11 - 45
-17y = -34
y = -34 / -17
y = 2
>> x = 9 - 3y
x = 9 - 3(2)
x = 9 - 6
x = 3