An explosives company specializes in bringing down old buildings. The time it takes for a particular piece of flying debris to fall to the ground can be modelled by the function h left parenthesis t right parenthesis equals negative 12 left parenthesis t plus 2 right parenthesis squared plus 120 left parenthesis t plus 2 right parenthesis, where h is the height of the debris, in metres, and t is the time, in seconds.

How long will it take for the piece of debris to hit the ground after an explosion? Show all work.