Question

Решить функцию xy=-30 x+y=1

Answer 1

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)