Calculus/Algebra

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Question
Susan throws a softball upward into the air at a speed of 32 feet per second from a 104-foot platform. The distance upward that the ball travels is given by the function d(t)=-16t^2+32t+104. What is the maximum height of the softball? How many seconds does it take to reach the ground after first being thrown upward?

Answer
When the softball attains maximum height, d(t)/ dt =0
ie  -32t +32 =0

      t=1 s

When t=1, height = -16 (1)^2 +32 (1) +104 =120 feet (shown)

When it reaches the ground, height above ground = 0 ft

ie  -16 t^2 +32t +104 =0

     2t^2 -4t - 13 =0    (dividing both sides by -8)

Hence,  t= 3.74s  (shown)   or  t=-1.74s (rejected)

Hope this helps. Peace.  

Calculus

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Frederick Koh

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I can answer questions concerning calculus, complex numbers, vectors, statistics , algebra and trigonometry for the O level, A level and 1st/2nd year college math/engineering student.

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More than 7 years of experience helping out in various homework forums. Latest Presence is over at http://www.thestudentroom.co.uk/ . You can also visit my main maths website http://www.whitegroupmaths.com where I have designed "question locker" vaults to store tons of fully worked math problems. A second one is currently being built. Peace.

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