Question

Как решить?
{X+Y=10
{x2-y2=40

Answer 1

$left { {{x+y=10} atop {x^2-y^2=40}} right. \left { {{x+y=10} atop {(x-y)(x+y)=40}} right. \ left { {{x+y=10} atop {(x-y)*10=40}} right. \ left { {{x+y=10} atop {x-y=4}} right. \ left { {{x=10-y} atop {10-y-y=4}} right. \ left { {{x=10-y} atop {10-2y=4}} right. \ left { {{x=10-y} atop {2y=6}} right. \ left { {{x=10-y} atop {y=3}} right. \ left { {{x=7} atop {y=3}} right.$
проверяем:
$left { {{7+3=10} atop {7^2-3^2=49-9=40}} right.$
ответ: (7;3)