No municipality shall exercise the authority hereafter conferred upon municipalities by this chapter until after it has voted by a majority of the voters present and voting on the question at a regular or special meeting duly warned for such purpose to adopt a resolution finding that: (1) one or more slum or blighted areas exist in such municipality; and (2) the rehabilitation, conservation, redevelopment, or a combination thereof, of such area or areas is necessary in the interest of the public health, safety, morals, or welfare of the residents of such municipality.