SOLUTION: Skydiving. If a skydiver jumps from an airplane at a height of 8256 feet, then for the first five seconds, her height above the earth is approximated by the formula h(t )16t2

Algebra ->  Human-and-algebraic-language -> SOLUTION: Skydiving. If a skydiver jumps from an airplane at a height of 8256 feet, then for the first five seconds, her height above the earth is approximated by the formula h(t )16t2       Log On


   

Question 195271: Skydiving. If a skydiver jumps from an airplane at a
height of 8256 feet, then for the first five seconds, her
height above the earth is approximated by the formula
h(t )16t2  8256. How many seconds does it take
her to reach 8000 feet?
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!

Your height function is a bit askew. If h(t) is to give you the height for a given time t, unless your skydiver is wearing a rocket pack that will make her height increase as time passes, then the height function has to be:



What you need is to figure out what value of t will make h(t) = 8000, i.e.



So just solve the quadratic for t. Exclude any negative root -- quite obviously she didn't reach 8000 feet any time before she jumped, right?

John