Question

Explain how you find instantaneous velocity and find it for s(t) = -3 + 4t^2 when t = 5 seconds.

Answer 1

You take the derivative of the position equation  s(t) = -3 + 4$t^{2}$
and you get  v(t) = 8t
now plug in 5 
v(5) = 40
40 m/s is your answer