Apopulation of bacteria is introduced into a culture. the number of bacteria p can be modeled by p=500(1+4t/(50+t^2 )) where t is time in hours. find the rate of change in population when t=2

How do you solve a question like this?

Find the roots of the polynomial function f(x) = x^3 + 2x^2 + x

Why can't my rank go i have 1723 points, but my rank is only at ambitious, which is only 250 points! like, (p. s. i know this isn't related to math, but i just don't know why it's doing this and i would really appreciate if someone could tell me whats going on with this)