Calculus Displacement Velocity Acceleration Approching and Accelerating Application

Q3. The motion of a particle is described by the function
s(t) = t3 – 12t2 + 45t + 3, t  0, where time t is measured in seconds and s, in meters.

a. When is the particle at rest?
b. When is the object moving in the negative direction?
c. When is the acceleration positive?
d. Is the particle moving towards or away from its initial position when the acceleration is zero?
Thanks