dv = adt integral from v(0) to v(t) of dv = integral from 0 to t of adt or (2t + 8)dt
v - v(0) = t2 + 8t v = t2 + 8t + 10 m/s
I hate that calculus books throw in speed and distance into these calculations!
Strictly, displacement or x - x(0) = integral from 0 to 10 of vdt.
This integral is only equal to the distance if |vdt| is calculated. For this problem, the velocity is positive-definite, so we can write
distance = integral from 0 to t of vdt.
I'll leave that to you to integrate. .