Help this is due in 20 minutes

Question

If a ball is thrown directly upward with a velocity of 38 ft/s, its height (in feet) after t seconds is given by y = 38t − 16t².What is the maximum height attained by the ball? (Round your answer to the nearest whole number.)

Answer 1

y = -16t² + 38t

Maximum occurs at t = -b / 2a, or t = -38 / 2(-16)

Can you substitute for t and answer?