Question

The yearly profit of a company in thousands of dollars can be modeled by P(t) = t4 − 5t2 + 4, where t is the number of years since 2000. Factor to find the years in which the profit was 0.

Answer 1

(t^2-1)(t^2-4)
so t=(-1, 1, -2, 2)
Time moves in one direction to our knowledge so disregard negative values.
depending on context, 1st and 2nd yr