SOLUTION: 3.h(t)=−4.9t2+8t+5 represents Jeremiah's height (h) in meters above the water t seconds after he leaves the diving board. Show clear solutions thanksss! a. What is the initial

Algebra ->  Functions -> SOLUTION: 3.h(t)=−4.9t2+8t+5 represents Jeremiah's height (h) in meters above the water t seconds after he leaves the diving board. Show clear solutions thanksss! a. What is the initial      Log On


   



Question 1172181: 3.h(t)=−4.9t2+8t+5 represents Jeremiah's height (h) in meters above the water t seconds after he leaves the diving board. Show clear solutions thanksss!
a. What is the initial height of the diving board?
b. At what time did Jeremiah reach his maximum height?
c. What was Jeremiah’s maximum height?
d. How long was Jeremiah in the air

Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
The 5 represents the diving board's height in m; the 8t is the speed leaving the board in m/sec and the -4.9 is the acceleration of gravity.
maximum height is at t=-b/2a or -8/-9.8 or 0.816 seconds
His maximum height was 8.27 m (I didn't round until the end). This is f(0.816)
he was in the air until h(t)=0 with positive t (the parabola has a negative t which is ignored)
rewrite as 4.9t^2-8t-5=0 (easier to deal with)
t=(1/9.8)(8+/-sqrt(64+98)) sqrt (162)=12.73
t=2.12 sec. in the air.
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