A particle moves along the x- axis so that at time t> 0 its position is given by x(t) = 3t^3 -27t^2 72t. Determine all intervals when the speed of the particle is decreasing.

A particle moves along the x-axis so that at time t _ 0 its position is given by a(t) = 3+3 - 27t2 + 72t. Determine all intervals when the speed of the particle is decreasing. Answer: Submit Answer or U S 2 (] (, ) All Real Numbers