I need help with a question asking if the particle is speeding up or slowing down. A particle moves on a vericle line. It's position, s, in metres at t seconds is given by s(t)= t^3-9t^2+24t a) determine the velocity and acceleration functions I got v(t)= 3t^2-18t+24 and a(t)= 6t-18 b) When is the particle moving up? Down? I got when 0<t<2, t>4 and it's slowing down at 2<t<4 c) When is the particle speeding up? Slowing down? I thought that I have to use a similar method to part b and make an interval chart, but I don't think I'm doing it right. I used the a(t) function and found the zero and used that in the chart. Can someone help me out? Thanks.