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9. [-10.24 Points] DETAILS LARCALCETI 5.1 .065.MI. MY NOTES | ASK YOUI Consider a particle moving along the xaxis where x(t) is the position of the particle at time t, x'(t) is its velocity, and x\"(t) is its acceleration. X(t) = t3- 12t2+21t9, Usts 10 (a) Find the velocity and acceleration of the particle. x'(t) = x\"(t) = (b) Find the open t-intervals on which the particle is moving to the right. (Enter your answer using interval notation.) (c) Find the velocity of the particle when the acceleration is 0. Need Help? _