Question

Решить систему уравнений x+y=3x^2+y^2=25+2xy

Answer 1

$x+y=3\\ x^2+y^2-2xy=25\\ \\ x+y=3\\ (x-y)^2=25\\ \\ x+y=3\\ x-y=5\\ \\ 3-y=5+y\\ -2=2y\\ y=-1\\ x=4\\ \\ x+y=3\\ x-y=-5\\ 3-y=y-5\\ 8=2y\\ y=4\\ x=-1$