4. (8 points) The acceleration (in m/s') and the initial velocity of a particle moving in a line is a(t) = t + 4 and 12(0) = 5 a) Find the velocity at time t. b) Find the distance travelled during the first 10 seconds. 5. (4 points) Explain, using words and pictures, why the following is true: J:f(x) dx = J:f(x) dx + Lbx) dx