$6.$ An object moves along a straight line so shat its position, s metres, at time it seconds, is given by: $x=5+12t-4t^2+2t^3$

$4.$ Find an expression for the velocity.

$(1$ mark$)$

b$.$ Find an expression for the acceleration.

$(1$ mark$)$

c$.$ Use your equations to write down the initial position and velocity.

d$.$ Find the time when the minimum velocity is achieved, and the value of the minimum velocity.