Question

система ровнений 9 класс

х-4у=3;
xy+2y=9

Answer 1

x = 4y+3
y(4y+3) + 2y = 9

x = 4y + 3
4y^2 + 3y + 2y = 9

x = 4y+3
4y^2 + 5y -9 = 0

D = 25+9*16=169
y = (-5 +- 13)/8

y1 = 1 -> x1 = 4+3 = 7
y2 = -2,25 ->x2 = -9 + 3 = -6

Ответ: (7;1), (-6;-2,25)