The population (in thousands) of a colony of bacteria t minutes after the introduction of a toxin is given by the function

p(t)= (piecewise) t^2+1 if 0(greater than or equal to)t< 5
-8t+66 if t is greater than or equal to 5

a. when does the colony die out?
b. show that at some time between t=2 and t=7, the population is 9,000