(x+y=8,
(2xy+4y²=256-x²

x+y=8,

2xy+4y²=256-x²

х = 8-у

2(8-у)у + 4у² = 256 - (8-у)²

16у - 2у² + 4у² = 256 - 64 + 16у - у²

3у² = 192

у² = 64

у₁ = 8, х₁ = 8-8 = 0

у₂ = -8, х₂ = 8 - (-8) = 16