Please help me with question 3 c and d

#3) A particle moves along a line so that its position at any time t 2 0 is given by the function s (t) = - t3 +7t2 -16t + 8 where s is measured in meter and t is measured in seconds. a) Find the instantaneous velocity at any time t. V(t) = S' () = 362 + lut b) Find the acceleration of the particle at any time t. Q (t ) = v ( t ) = 6t+ 12c) When is the particle at rest? d) What is the displacement of the particle for the 3 seconds