If `X=(x:x^(2)-12x+20=0)` and `Y=(x:x^(2)+5x-14=0)` , then X-Y=

If x=k is the equqtion of a common tangent to the curves 9x^(2)+16y^(2)=144 ,y^(2)-x+4=0 and x^(2)+y^(2)-12x+32=0 then k is equal to _____

The equation of the tangent at the point (0, 3) on the circle which cuts the circles x^(2)+y^(2)-2x+6y=0 , x^(2)+y^(2)-4x-2y+6=0 and x^(2)+y^(2)-12x+2y+3=0 orthogonally is

x^(2) + x-20= 0, y^(2)-y-30=0

(i) x^(2) - 5x-14 = 0 (ii) 2y^(2) +11y + 14 = 0