- S(x,y)=0 represents a circle. The equation S(x,2)=0 gives two identical solutions x=1 and the equation S(1,y)=0 gives two distinct solutions y=0,2 , then the equation of the circle is
a. x2+y2+2x−2y+1=0
b. x2+y2−2x+2y+1=0
c. x2+y2−2x−2y−1=0
d. x2+y2−2x−2y+1=0