Решение систем уравнений второй степени

X - 2y = -1
x² + 8y = 9

x = 2y - 1
(2y -1)² + 8y - 9 = 0

x = 2y - 1
4y² - 4y + 1 + 8y - 9 = 0

x = 2y - 1
4y² + 4y - 8 = 0

x = 2y - 1
y² + y - 2 = 0

y1 + y2 = -1
y1•y2 = -2

y1 = -2
y2 = 1

y = -2
x = 2y - 1

y = 1
x = 2y - 1

y = -2
x = -5

y = 1
x = 1
Ответ: (-5; -2), (1; 1).