Equation of tangent of ellipsoid of a space curve | differential geometry for BSCmaths lecture 7

show that the equation of tangent of a curve if intersection the ellipsoid x square upon a square + y square upon b square + z upon c square is equal to 1 is confocul of x square upon a square minus lambda plus y square upon b square minus lambda + z square upon C square minus k lambda is equal to 1 where lambda is a parametric quantity then x(X-x)/ a^2(b square minus C square)( A2 - lambda)=y(Y-y)/