3. A particle moves in a straight horizontal line such that its velocity, \(v \mathrm {~m} \mathrm {~s} ^ { - 1 }\), at time \(t\) seconds is given by \(v = 2 t ^ { 2 } - 9 t + 4\). Initially, the particle has displacement 9 m from a fixed point \(O\) on the line.

1. Find the initial velocity of the particle.
2. Show that the particle is at rest when \(t = 4\) and find the other value of \(t\) when it is at rest.
3. Find the displacement of the particle from \(O\) when \(t = 6\).