A. x2+ax+b=0

B. x2-ax+b=0

C. x2+ax-b=0

D. x2-ax-b=0

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

If 4y=x+7 is diameter of the circumscribing circle of the rectangle ABCD and A(-3, 4), B(5, 4), then the area of the rectangle is

The polar of the point(2t, t-4) w.r.t the circle x^{2}+y^{2}-4x-6y+1=0 passes through the point