x=3-y
(3-y)^2+y^2=49
9-6y+y^2+y^2-49=0
2y^2-6y-40=0 :2
y^2-3y-20=0
D=9+80=89
y1=(3+√89) /2
y2=(3-√89) /2
x1=3- (3+√89) /2 = ( 6-3-√89) /2 = (3-√89)/2
x2=3-(3-√89)/2 = ( 6-3+√89)/2 = (3+√89)/2
x=3-y
(3-y)^2+y^2=49
9-6y+y^2+y^2-49=0
2y^2-6y-40=0 :2
y^2-3y-20=0
D=9+80=89
y1=(3+√89) /2
y2=(3-√89) /2
x1=3- (3+√89) /2 = ( 6-3-√89) /2 = (3-√89)/2
x2=3-(3-√89)/2 = ( 6-3+√89)/2 = (3+√89)/2