Question

{(x+y)^2=25
{x+y=-5 помогите пожалуйста

Answer 1

$left { {{ (x+y^{2})=25} atop {x+y=-5}} right.$
$left { {{ (x^2+2xy+y^2})=25} atop {x=-5-y}} right.$
$(-5-y)^2+2y(-5-y)-y^2=25$
$25+10y-10y-2y^2-y^2=25$
$-3y^2=0$
$y=0$
x=-5-0
x=-5