The equation to the pair of lines joining the origin to the points of intersection of y = x+3 and 2x2+2y2=1 is
12(x2+y2)=(x−y)2
6(x2+y2)=(x−y)2
18(x2+y2)=(x−y)2
2(x2+y2)=(x−y)2
x−y−3=1⇒apply homogenization
2x2+2y2=y−x32