Question

система
x^2+y^2=13
x-y=-1

Answer 1

x=y-1
y^2-2y+1+y^2=13
2y^2-2y-12=0
y^2-y-6=0
D=25
y=(1+-5)/2=3; -2
x= 2; -3
(2;3), (-3;-2)