Question

$9x ^{2} + 6xy + y ^{2} = 1 \\ 3xy + y ^{2} = - 2$

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Answer 1

3xy + y² = -2

y(3x + y) = -2

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9x² + 6xy + y² = 1

(3x + y)² = 1

3x + y = +-1

1. 3x + y = 1

y = -2

3x - 2 = 1

x = 1

2. 3x + y = -1

y = 2

3x + 2 = 1

x = -1/3

ответ (1,-2)(-1/3,2)