$s ( t )$ Is the Position of a Body Moving Along a Coordinate

Essay

$s ( t )$ is the position of a body moving along a coordinate line, where $t \geq 0$ , and $s ( t )$ is measured in feet and $t$ in seconds.
$$s ( t ) = - 3 + 2 t - t ^ { 2 }$$
a. Determine the time(s) and the position(s) when the body is stationary.
b. When is the body moving in the positive direction? In the negative direction?
c. Sketch a schematic showing the position of the body at any time $t$ .