Show that plane `ax+by+cz+d=0` divides the line segment joining `(x_1,y_1,z_1) and (x_2,y_2,z_2)` in a ratio `-(ax_1+by_1+cz_1+d)/(ax_2+by_2+cz_2+d)`

Answer

`-(( a x_(1) + b y_(1) + cz_(1) + d)/(a x_(2) + b y_(2) + c z_(2) + d))`