4. (7 points) A particle moves according to the law s = f(t) = t* 6t + 9t ere t 1s measured in seconds and s in meters. a. Find the velocity at time t. b. What 1s the velocity after 2 s and after 4 s? c. When is the particle at rest? d. When is the particle moving in the positive direction? e. Find the total distance traveled by the particle during the first 5 seconds. f. Find the acceleration at time t and after 4 s. g. When 1s the particle speeding up? When it 1s slowing down