I need help with a question asking if the particle is speeding up or slowing down.(adsbygoogle = window.adsbygoogle || []).push({});

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.

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# Homework Help: When is a particle speeding up or slowing down?

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