Question

Решите систему уравнений (a)

Answer 1

$\left \{ {{xy-3=-4x} \atop {xy+6=y}} \right.$
$\left \{ {{y- \frac{3}{x}=-4 } \atop {y+4x=9}} \right.$
$\left \{ {{y=9-4x} \atop {9-4x- \frac{3}{x}=-4}} \right.$
$\left \{ {{y=9-4x} \atop {9x-4 x^{2} -3=-4x}} \right.$
$\left \{ {{y=9-4x} \atop {4 x^{2} -13x+3=0}} \right.$
$4 x^{2} -13x+3=0$
$D=169-48=121$
$x= \frac{13+- \sqrt{121} }{8}$
$x_{1} =3, x_{2} =0,25$
$\left \{ {{y=-3} \atop {x=3}} \right., \left \{ {{y=7} \atop {x=0,25}} \right.$