A particle moves along the x-axis so that at time t its position is given by s(t) = (t + 1)(t − 3)3, t > 0. For what values of t is the velocity of the particle increasing?

t > 3
1 < t < 3
0 < t < 1 and t > 3
t > 0

Sanya noticed that the temperature was falling at a steady rate of 1.4 degrees every hour from the time that she first checked her outdoor thermometer. by 6 a.m., the temperature had fallen 21 degrees. which expression can you use to find how many hours earlier she had first checked the thermometer?