The function y = -16x2 + 1500 gives a parachute jumper's height y in feet after "X" seconds for a jump from 1500 feet. How long is free fall if the
parachute opens at 1100 feet?

Step-by-step explanation:

so the question is asking about the time from 1500 feet to 1100 feet.  How long did they fall, w/o a parachute.    aka   "freefall"   so,   at 1500 feet the jumper is really at time zero.   so, plug in to the formula

1100 = -16 +1500  

( x represents seconds so i'll change it to t so we know it's time )  

1100 = -16 + 1500

now we can solve for t  , to see how long the jumper falls

-400 = - 16      ( subtracting 1500 from both sides of equation )

25 =      ( dividing both sides by  -16 )

oh.. look at how nice that turns out.. :)

= t  ( take the square root on both sides )

5 = t    

the jumper fell for 5 seconds to get to 1100 feet  

17 1/3

step-by-step explanation: