SOLUTION: If a skydiver jumps from a airplane at a height of 8,256 ft, then for the first 5 seconds, her height above the earth is approximated by the formula, h= -16t^2 + 8,256. How many s

Question 151528: If a skydiver jumps from a airplane at a height of 8,256 ft, then for the first 5 seconds, her height above the earth is approximated by the formula, h= -16t^2 + 8,256. How many seconds does it take her to reach 8,000 ft?
Answer by Earlsdon(6294) (Show Source): You can put this solution on YOUR website!
Starting with the given equation:, you want to find at what time, t, will h = 8000.
Subtract 8000 from both sides.
Multiply through by -1.
Notice that the binomial is the difference of squares, so you can factor this nicely...
Now apply the zero products rule.
or
If then and
If then and
Discard the negative answer because the time, t, should be positive.
It take 4 second for the skydiver to reach a height of 8,000 feet.
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