Limiting points of the coaxial system

The limiting points of the coaxal system x^(2) + y^(2) + 2 lambda x + 4 = 0 are

The limiting points of the coaxal system x^(2) + y^(2) +2 muy + 9 = 0 are

Origin is a limiting point of a coaxial system of which x^(2)+y^(2)-6x-8y+1=0 is a member. The other limiting point, is

Origin is a limiting point of a coaxial system of which x^(2)+y^(2)-6x-8y+1=0 is a member. The other limiting point, is

If (1, 2) is a limiting point of a coaxial system of circles containing the circle x^(2)+y^(2)+x-5y+9=0 , then the equation of the radical axis, is