Problema Solution
The following formula models the number of prison inmates, P, in thousands, who are in U.S. prisons x years after 1980.
P = 2 x^2+20 x+320
Find the first year after 1980 in which the population of U.S. prisons was approximately 320 thousand people.
Answer provided by our tutors
P(x) = 2 x^2+20 x+320, where x is the years after 1980, P(x) the population in thousands
we need to find such x so that P(x) = 320 that is
2 x^2+20 x+320 = 320
and this happens for x = 0 thus in the year of 1980 the population of US prisons was 320 thousand people.