Position when particle achieves maximum speed on x-axis

[J.live]

Homework Statement

The position of a particle moving along the x-axis is given by x = 4.7t2 − 3.2t3,where x is in meters and t is in seconds. What is the position of the particle when it achieves its maximum speed in the positive x-direction?

 

[zorro]

You should try to attempt the problem along with the question!
I cannot help you unless you try to do it.