» II.- Sistemas de ecu. 2º grado con dos incógnitas

1.249

$\large x(1+5y+\frac{y}{x})=31$
$\large xy=\: \: 5$

1.250

$\large x-xy+y=\frac{11}{6}$
$\large 3xy=\: \: 7$

1.251

$\large x+xy-y=16$
$\large xy=12$

1.252

$\large x-y(3x+1)=-\frac{1}{3}$
$\large 5xy=\: \: 1$

1.253

$\large x+\sqrt{xy}+y=14$
$\large xy=16$

1.254

$\large x-\sqrt{xy}-y=10$
$\large xy=36$

1.255

$\large x^{2}+y^{2}+3y+y=20$
$\large x-y=\: \: 2$

1.256

$\large 2x^{2}+3y^{2}-x-5y=26$
$\large 3x-2y=10$

1.257

$\large x^{2}-xy=-52$
$\large \frac{x-1}{y-1}=\frac{3}{4}$

1.258

$\large (x+2)+(y+3)=11$
$\large (x+2)\: \: (y+3)=24$

1.259

$\large (x-4)+(y-7)=3$
$\large (x-4)\: \: (y-7)=2$

1.260

$\large (x+3)(y+4)=48$
$\large x+y=\: \: 9$

1.261

$\large (x+2)(y-7)=\: \: 4$
$\large x+y=14$

1.262

$\large x^{2}+y^{2}+x-5y=24$
$\large x+y=\: \: 7$

1.263

$\large 3x^{}+xy+2y^{2}+3x+2y=39$
$\large 2x+3y=\: \: 3$

1.264

$\large (x+y)^{2}-(x-y)^{2}=40$
$\large x+3xy-y=21$

1.265

$\large (x+y)^{2}-(x-y)^{2}=28$
$\large x-xy+y=\: \: 1$

1.266

$\large (x+1)^{2}+(y+1)^{2}=52$
$\large 2(x+4)+3(y-2)=23$

1.267

$\large (x+2)^{2}+(y+3)^{2}=32$
$\large 5x+4y=14$