9. A particle moves in a straight line so that, t seconds
after leaving a fixed point A, its velocity, v m/s, is
given by $v = 4e^t - 5e^{1 - 2t}$. Find
(i) the value of t when the particle is at
instantaneous rest,
(ii) the distance travelled by the particle in the
2nd second of its motion,
(iii) the average speed of the particle for the first
3 seconds of its motion.
