Answer:
5.2 seconds
Step-by-step explanation:
h(t) = -16t^2 +64t+100
Let h(t) =0
0 = -16t^2 +64t+100
Factor out -4
0 = -4( 4t^2 - 16t -25)
Divide by -4
0 = ( 4t^2 - 16t -25)
Using the quadratic formula
-b ±sqrt( b^2 -4ac)
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2a
16 ±sqrt ( (16)^2 - 4(4)(-25))
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2(4)
16 ±sqrt ( 256 +400)
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8
16 ±sqrt ( 656)
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8
16 ±4sqrt ( 41)
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8
2 ±1/2 sqrt ( 41)
5.2 and -1.2
We cannot have negative time so
5.2
