ENEM 2016 - 2ª Aplicação - Função do 2º Grau - Para evitar uma epidemia, a Secretaria de Saúde de um

To prevent an epidemic, the Health Department of a city fumigated all neighborhoods to prevent the proliferation of the dengue mosquito. It is known that the number f of infected people is given by the function f(t) = –2t² + 120t (where t is expressed in days and t = 0 is the day before the first infection) and that this expression is valid for the first 60 days of the epidemic. The Health Department decided that a second fumigation should be carried out on the day the number of infected people reached 1,600, and a second fumigation was necessary. The second fumigation began on the 19th day. 20th day. 29th day. 30th day. 60th day.