answer with explanation provided

4. A particle's displacement, s, as a function of time, t, along a line is given by the equation s (t) = 3t2 - 5t + 6. (a) Determine its instantaneous velocity after 6 seconds. [2] (b) Determine its acceleration after 6 seconds. [2] (c) At what values of t does the particle change direction? [2]