Rate of change.... derivative? 1. The problem statement, all variables and given/known data the total number of people(in millions) present in a population at a given time is given by the function: 2t(5t+9)^1/2+12 where t represents time (in hours) find the rate in change of the population after 2.5 hours... 2. Relevant equations 3. The attempt at a solution im so confused do i find the derivative ?