A. x2/a2+y2/b2=a

B. x2/a2+y2/b2=b

C. x2/a2+y2/b2=2

D. x2/a2+y2/b2=ab

If the variable line l_{1}(x-a)+y=0 and l_{2}(x+a)+y=0 are conjugate lines w. r. to the ellipse x^{2}/a^{2}+y^{2}/b^{2}=1. Then the locus of their point of intersection is

The locus of the poles w.r.t the ellipse x^{2}/a^{2}+y^{2}/b^{2}=1 of tangents to its auxiliary circle is

If the line lx+my=1 is a normal to the ellipse x^{2}/a^{2}+y^{2}/b^{2}=1 then a^{2}/l^{2}-b^{2}/m^{2}=1

The radius of the circle passing through the foci of the ellipse x^{2}/16+y^{2}/9=1 and having its center at (0, 3) is

If x and y are strictly positive such that x+y =1,then the minimum value of x log x + y log y is