A. x2+y2+8x+6y=0

B. x2+y2+4x-16y-101=0

C. x2+y2-4x-6y=0

D. x2+y2=5

The system of circles orthogonal to x^{2}+y^{2}+2x+4y+7=0 is a member, then the equation of the orthogonal system is

The circle described on the line joining the points (0, 1), (a, b) as diameter cuts the x-axis in points whose abscissa are roots of the equation

If the length of the tangent from (h, k) to the circle x^{2}+y^{2}=16 is twice the length of the tangent from the same point to the circle x^{2}+y^{2}+2x+2y=0, then

The equation of the circle concentric with circlex^{2}+y^{2}-6x+12y+15=0 and of double its area is

The equation of the circle passing through the points of intersection of the circlesx2+y2=5, x^{2}+y^{2}+12x+8y-33=0 and touching x-axis is