2х - 3y = - 18
Xy = - 12
Решение
2х = 3y - 18
X = 1,5y - 9
y( 1,5y - 9 ) = - 12
1,5y^2 - 9y + 12 = 0
D = 81 - 72 = 9 = 3^2
y1 = ( 9 + 3 ) : 3 = 4
y2 = ( 9 - 3 ) : 3 = 2
X = 1,5y - 9
X1 = 1,5•4 - 9 = - 3
X2 = 1,5•2 - 9 = - 6
Ответ ( - 3 ; 4 ) ; ( - 6 ; 2 )