Question

x-y=4
${x}^{2} - {y}^{2} = 40$
​

Answer 1

Объяснение:

$\left \{ {{x-y=4} \atop {x^2-y^2=40}} \right. \ \ \ \ \left \{ {{x-y=4} \atop {(x-y)*(x+y)=40}} \right. \ \ \ \ \left \{ {{x-y=4} \atop {4*(x+y)=40\ |:4}} \right. \ \ \ \ \left \{ {{x-y=4} \atop {x+y=10}} \right..$

Суммируем эти уравнения:

$2x=14\ |:2\\x=7\ \ \ \ \Rightarrow\\7-y=4\\y=3.$

Ответ: (7;3).