Question

Método por igualación:
1. 5x + 7y =
3x – 2y = 3
1. 6x - 5y = 9
9x + 7y = -1
2. x+y=1
X-2y = -1

Answer 1

1)

5x + 7y =

3x - 2y = 3

Falta un término a la primera ecuación

2)

6x - 5y = 9

9x + 7y = -1

9 + 5y -1 - 7y

_____ = ______

6 9

9 (9 + 5y) = 6 (-1 - 7y)

81 + 45y = -6 - 42y

45y + 42y = -6 - 81

87y = -87

y = -87/87

y = -1

6x - 5y = 9

6x - 5(-1) = 9

6x + 5 = 9

6x = 9 - 5

6x = 4

x = 4/6

x = 2/3

9x + 7y = -1

9x + 7(-1) = -1

9x - 7 = -1

9x = -1 + 7

9x = 6

x = 6/9

x = 2/3

R// x = 2/3; y = -1

3)

x + y = 1

x - 2y = -1

1 - y = -1 + 2y

-y - 2y = -1 - 1

(-) -3y = -2

3y = 2

y = 2/3

x + y = 1

x + 2/3 = 1

x = 1 - 2/3

x = 3 - 2/3

x = 1/3

x - 2y = -1

x - 2(2/3) = -1

x - 4/3 = -1

x = -1 + 4/3

x = -3 + 4/3

x = 1/3

R// x = 1/3; y = 2/3

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