Xy = - 30
x = 1 - y
(1 - y) y + 30 = 0
y - y^2 + 30 = 0
y^2 - y - 30 = 0
D = 1 + 120 = 121
y1 = ( 1 + 11)/2 = 12/2 = 6
y2 = ( 1 - 11)/2 = - 10/2 = - 5
x1 = 1 - y1 = 1 - 6 = - 5
y1 = 6
x2 = 1 - y1 = 1 + 5 = 6
y2 = - 5
Ответ
( - 5; 6) ;
(6 ; - 5)
1)5÷4×7×p^3×p^2×q^4 ×q = 140p^5q^5
2)3/2 : (1/4 +2/4) - 2,7 = 3/2 : 3/4 - 2,7 =3/2 × 4/3 - 2,7 = 2 - 2,7 = - 0,7