Система ровнений 9 класс х-4у=3; xy+2y=9

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)

X-4y=3⇒x=4y+3
xy+2y=9
4y²+3y+2y-9=0
4y²+5y-9=0
D=25+144=169
y1=(-5-13)/8=-2,25⇒x1=-9+3=-6
y2=(-5+13)/8=1⇒x2=4+3=7
(-6;-2,25);(7;1)