1.18: Distance when a particle is instantaneously at rest

A particle $\displaystyle P$ is moving in a straight line. At time $\displaystyle t$ seconds, $\displaystyle t\geq0$, the displacement, $\displaystyle s$ metres, of $\displaystyle P$ from a fixed point $\displaystyle O$ of the line is given by

Find the distance of $\displaystyle P$ from $\displaystyle O$ when $\displaystyle P$ is instantaneously at rest.