Hi can someone help me figure this out:

position of a particle (s) at time t:

s = 2t^3 + 18t^2 - 672t

I found the total distance traveled during the first 19 secs is 7448 (right?)

I need help figuring this out:

the particle is at rest after ___ seconds. <- is it 8? the answer doesn't work

also, The particle is moving forward in the time interval t>8 and backward in the time interval t<8, is this right?

thanks!