A body moves in rectilinear motion along the x-axis with an acceleration of a = 24 - t - 6 t^2 . Starting with an initial position at the origin (x = 0) and an initial velocity of 4 ft/s to the left (along the negative x-axis), what is the position of the body at the end of 4 s .

a = 24 - t - 6 t^2

v = Vi + 24 t - .5 t^2 - 2 t^3
x = Xi + Vi t + 12 t^2 - (.5/3)t^3 - .5t^4
put in Xi =0
Vi = -4
t = 4
plug and chug