In Exercises 13 through 18, refer to the following. Suppose a ball is thrown straight upward with an initial velocity (that is, velocity at the time of release) of 128 ft/sec and that the point at which the ball is released is considered to be at zero height. Then the height s(t) in feet of the ball at time t in seconds is given by s(t)=-16t + 128t. Let v(t) be the instantaneous velocity at time t. Find v(t) for the indicated values of t. 13. v(1) 16. v(5) 14. v(3) 17. v(6) 15. v(4) 18. v(7) 19. Find the equation of the line tangent to the curve s = -16t + 64t at the point (1.48). Support your answer 35. Ident tange