Решите систему уравнений 1)х^2 + 10ху +25у^2= 9
2) х-5у=7

{ x² + 10xy + 25y² = 9{ x - 5y = 7{ (x + 5y)² = 9{ x = 5y + 7(5y + 7 + 5y)² = 9(10y + 7)² = 3²10y + 7 = 3                  10y + 7 = -3          y = -0,4                          y = -1                     x = 5                              x = 2                    Ответ: {5; -0,4}, {2; -1}