Question

Теңдеулер жүйесін шешіңіз:
x²+y²=113
x+y=15​

Answer 1

Объяснение:

$\left \{ {x^2+y^2=113} \atop {x+y=15}} \right. \ \ \ \ \left \{ {{x^2+2xy+y^2=113+2xy} \atop {x+y=15}} \right.\ \ \ \ \left \{ {{ (x+y)^2=113+2xy} \atop {x+y=15}} \right. \ \ \ \ \left \{ {{15^2=133+2xy} \atop {x+y=15}} \right. \\\left \{ {{2xy=225-113} \atop {y=15-x}} \right.\ \ \ \ \left \{ {{2xy=112\ |:2} \atop {y=15-x}} \right.\ \ \ \ \left \{ {{xy=56} \atop {y=15-x}} \right. \ \ \ \ \left \{ {{x*(15-x)=56} \atop {y=15-x}} \right. \ \ \ \ \left \{ {{15x-x^2=56} \atop {y=15-x}} \right.$

$\left \{ {{x^2-15x+56=0} \atop {y=15-x}} \right. \ \ \ \ \left \{ {{D=1\ \ \sqrt{D}=1 } \atop {y=15-x}} \right. \ \ \ \ \left \{ {{x_1=7\ \ x_2=8} \atop {y_1=8\ \ y_2=7}} \right. .$

Ответ: (7;8), (8;7).