Решите систему уравнений
{x-y=1
{x2-y=3

x = y + 1
(y + 1)^2 - y - 3 = 0 *

y^2 + 2y + 1 - y - 3 = 0
y^2 + y - 2 = 0
D = 1 + 4*2 = 9
y1 = ( - 1 + 3)/2 = 1
y2 = ( - 1 - 3)/2 = - 2

x1 = y1 + 1 = 1 + 1 = 2
y1 = 1

x2  = y2 + 1 = - 2 + 1 = - 1 
y2 = - 2 

Ответ
( - 1; - 2) ;
( 2; 1)