The pole of the straight line $x + 2y = 1$ with respect to the circle $x^2 + y^2 = 5$ is

If $A(2, c)$ and $B(d, 2)$ are two points such that the polar of one point with respect to the circle $x^2+y^2=16$ passes through the other,then $c+d=$

The normal to a circle $S=0$ at $P(1,3)$ is $x+2y=7$ and it has another normal at $Q(3,5)$ which is the polar of the point $A(7, -1/2)$ with respect to the circle $x^2+y^2-4x+6y-12=0$. Then,the equation of the circle $S=0$ is

If $5x + 6y - 34 = 0$ and $2x + y + c = 0$ are conjugate lines with respect to the circle $x^2 + y^2 - 8x - 10y + 25 = 0$,then which of the following points lies on the line $2x + y + c = 0$?

If $2kx + 3y - 1 = 0$ and $2x + y + 5 = 0$ are conjugate lines with respect to the circle $x^2 + y^2 - 2x - 4y - 4 = 0$,then $k =$

The point of concurrence of the polars of the variable point $(2t, t-4)$,where $t \in R$,with respect to the circle $x^2+y^2-4x-6y+1=0$ is