A. α2x2/a4+β2y2/b4=( x2/a2+y2/b2)2

B. α2x2/a4+β2y2/b4=( x2/a2-y2/b2)2

C. α2x2/a4+β2y2/b4=( x2/a2+y2/b2)2

D. α2x2/a4-β2y2/b4=( x2/a2-y2/b2)2

The points on the ellipse x^{2}/25+y^{2}/9=1 whose angles differ by a right angle are

The chord of contact of tangents drawn from points on x^{2}/a^{2}+y^{2}/b^{2}=1 to the circle x^{2}+ y^{2}=c^{2 }touches the ellipse

The tangents are drawn to the ellipse x^{2}/a^{2}+y^{2}/b^{2}=1 at point where it is intersected by the line lx+my+n=0. The point of intersection of tangents at these points is

If the lines 4x+3y-1=0,x-y+5=0 and kx+5y-3=0 are concurrent,then k is equal to

The product of the slopes of the tangents to the ellipse 2x^{2}+3y^{2}=6 draw from the point (1, 2) is