The lines which intersect the skew lines y=mx,z=c;y=−mx,z=−c  and the x-axis lie on the surface

Equations of the planes through  y=mx,z=c;y=−mx,z=−c  are respectively, (y−mx)+λ1(z−c)=0------1and  (y+mx)+λ2(z+c)=0----2It meets at x-axis, i.e., y= 0 = z. ∴ λ2=λ1From(i)and(ii), y−mxz−c=y+mxz+ccy=mxz