The correct option is B x2+y2+4x+2y=0
Equation of a tangent to y2=4x in slope form is
y=mx+1m (∵a=1)
It also touches x2=32y
∴x2=32(mx+1m) has equal roots.
⇒x2−32mx−32m=0 has equal roots.
⇒D=0⇒(−32m)2+4(32m)=0
⇒m3=−18
⇒m=−12
∴ Equation of common tangent is x+2y+4=0
Here, A=(−4,0), B=(0,−2)
Equation of circumcircle of ΔOAB is
(x+4)(x−0)+(y−0)(y+2)=0 (AB is diameter)
⇒x2+y2+4x+2y=0