Question 95647
a) If a rock is thrown upward with an initial velocity of 64 feet per second from the top of a 25-foot building, write the height (s) equation using this information. 
Typing hint: Type t-squared as t^2
Answer: s(t)=-16t^2+64t+25 
Correct
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b) How high is the rock after 1 second?
Answer:s=73 
Show your work here: 
S(1)=-16(1^2)+64(1)+25
S(1)=-16+64+25
S(1)=73 ft. 
Correct
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c) After how many seconds will the graph reach maximum height? 
Answer: 
Your height function is a quadratic with a=-16, b= 64 , c=25
The maximum height occurs when t=-b/2a = -64/(2*-16) = 2 seconds
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d) What is the maximum height?
Answer:
Show your work here:
Find S(2) which is the height after 2 seconds
S(2) = -16(2^2)+64(2)+25 
S(2) = -64+128+25 = 89 ft
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Cheers,
Stan H.