The position of a particle moving along the x-axis is given by x = 6.0t² − 1.0t³, where x is in meters and t in seconds. What is the position of the particle when it achieves its maximum speed in the positive x direction?
a) x = 0
b) x = 6.0 meters
c) x = 9.0 meters
d) x = 12.0 meters
