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y - x + 6 / y + x = 6 - x / x
ĐK: $x \ne 0 ; x +y \ne 0$
pt $\iff (y-x+6) \cdot x = (6-x)(y+x)$
$\iff xy - x^2 + 6x = 6y - xy - x^2 + 6x$
$\iff 2xy - 6y = 0$
$\iff 2y(x-3) = 0$
$\iff y = 0$ hoặc $x = 3$
Vậy $x = 3 ; y \ne -3$ hoặc $x \ne 0 ; y = 0$