Question

Фигурная скобка: 2у-х=7 Х^2-ху-у^2=20

Answer 1

2у-х=7
х²-ху-у²=20
-x = 7-2y
x = 2y-7
(2y-7)^2 -y(2y-7) -y^2 = 20
4y^2 -28y +49 -2y^2 +7y -y^2 -20 =0
y^2 -21y +29 = 0
D = -21^2 -4 *1*29 = 325
$y1 = \frac{21- \sqrt{325} }{2}$
$y2 = \frac{21+ \sqrt{325} }{2}$