Question

Решите систему равнение
{x+y=10
{x^2-y^2=40
{x-y=4

Answer 1

$left { {{x-y=4} atop { x^{2}- y^{2} =40}} right.$
$left { {{x-y=4} atop { (x - y)(x+y) =40}} right.$
4(x + y) = 40
x + y = 10
$left { {{x-y=4} atop {x + y = 10}} right.$
2x = 14
x = 7
7 + y = 10
y = 3