Question 174663This question is from textbook Amsco's Preparing for the Regents Examination Mathematics B
: 5) Crossing a wooden bridge at Letchworth Park, Melissa drops a penny into the water below for good luck. If the height of the penny is modeled by the function h(t)=64 - 16t^2, where t represents time in seconds and h(t) is height in feet, how many seconds did it take the penny to hit the water?
(a) 1 (b) 2 (c) 3 (d) 4
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This question is from textbook Amsco's Preparing for the Regents Examination Mathematics B
Answer by nycsub_teacher(90)   (Show Source):
You can put this solution on YOUR website! Hello. I received your e-mail. You need more help, right?
Here is one of your questions:
5) Crossing a wooden bridge at Letchworth Park, Melissa drops a penny into the water below for good luck. If the height of the penny is modeled by the function h(t)=64 - 16t^2, where t represents time in seconds and h(t) is height in feet, how many seconds did it take the penny to hit the water?
(a) 1 (b) 2 (c) 3 (d) 4
Let h(t) = 0
0 = 64 - 16t^2
Subtract 64 from both sides.
-64 = -16t^2
Now divide both sides by -16.
-64/-16 = t^2
64/16 = t^2
4 = t^2
Finally take the square root of both sides of the equation.
sqrt{4} = sqrt{t^2}
2 = t
The answer is choice (b).
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