Question

Решите уравнение способам подстановки х^2+у^2=9 х+у=2

Answer 1

Объяснение:

$\left \{ {{x^2+y^2=9} \atop {x+y=2}} \right. \ \ \ \ \left \{ {{x^2+(2-x)^2}=9 \atop {y=2-x}} \right. \ \ \ \ \left \{ {x^2+4-4x+x^2-9=0} \atop {y=2-x}} \right. \ \ \ \ \left \{ {{2x^2-4x-5=0} \atop {y=1-x}} \right.$

$2x^2-4x-5=0\\D=56\ \ \ \ \sqrt{D}=2\sqrt{14} \\x_1=1-\frac{\sqrt{14} }{2}\ \ \ \ y_1=1+\frac{\sqrt{14} }{2} \\x_2=1+\frac{\sqrt{14} }{2} \ \ \ \ y_2=1-\frac{\sqrt{14} }{2} .$