вас! решить систему уравнений: x-5y=9 x^2-3xy-y^2= -27

X - 5y = 9
X = 5y + 9
X^2 - 3xy - y^2 = - 27
( 5y + 9 )^2 - 3y( 5y + 9 ) - y^2 = - 27
25y^2 + 90y + 81 - 15y^2 - 27y - y^2 = - 27
9y^2 + 63y + 108 = 0
9( y^2 + 7y + 12 ) = 0
D = 49 - 48 = 1 = 1^2
y1 = ( - 7 + 1 ) : 2 = - 3
y2 = ( - 7 - 1 ) : 2 = - 4
X1 = 5 • ( - 3 ) + 9 = - 15 + 9 = - 6
Х2 = 5 • ( - 4 ) + 9 = - 20 + 9 = - 11
ответ ( - 6 ; - 3 ) ; ( - 11 , - 4 )