Explanation:
We divide the problem in 3 parts: part 1 when the car accelerates, part 2 when its velocity is constant and part 3 when it slows down and we use the main equations for accelerated motion and , and for the last part
We start calculating the displacement and final velocity of part 1 considering the initial velocity is zero:
Now we calculate the displacement of part 2 considering the velocity remains constant since acceleration is zero:
Now we calculate the displacement of part 3 considering the initial velocity is the final velocity of the previous part and that it slows down until coming to rest:
So our total displacement is