The positions x of a particle with respect to time t along x-axis is given by x = 9t2 $-$ t3 where x is in metres and t in seconds. What will be the position of this particle when it achieves maximum speed along the + x direction ?

Question

The positions x of a particle with respect to time t along x-axis is given by x = 9t² $-$ t³ where x is in metres and t in seconds. What will be the position of this particle when it achieves maximum speed along the + x direction ?