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

${\mathcal{l}}_{1}x+m_{1}y+n_1=0$

${\mathcal{l}}_{2}x+mxy+n_2=0$

$x^2+y^2+2gx+2fy+c=0$

Condition for conjugate line

$(g^2+f^2-c)({\mathcal{l}}_1{\mathcal{l}}_2+m_1{m}_2)=({\mathcal{l}}_{1}g+m_{1}f-n_1)$

$\therefore K=1$

$({\mathcal{l}}_{2}g+m_{2}f-n_2)$