Answer:
a) 272 feet
b) 3 seconds
c) 7.123 seconds
Step-by-step explanation:
A graphing calculator provides an easy way to answer questions about the parameters of a quadratic function. Here the graph shows ...
a) the maximum height is 272 feet
b) it takes 3 seconds to get there
c) the rocket crashes after about 7.123 seconds
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You can solve this algebraically by rewriting the equation in vertex form.
h(t) = -16t² +96t +128 . . . . . . given
h(t) = -16(t² -6t) +128 . . . . . . . factor out leading coefficient
h(t) = -16(t² -6t +9) +128 -(-16)(9) . . . . complete the square
h(t) = -16(t -3)² +272 . . . . . . write in vertex form
The vertex of the height function is (3, 272) meaning the rocket reaches a maximum height of 272 feet after 3 seconds.
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The zero of the function can be found to be ...
0 = -16(t -3)² +272
0 = (t -3)² -17 . . . . . . divide by -16
t -3 = ±√17 . . . . . . add 17, take the square root
t = 3 +√17 ≈ 7.123106 . . . . . positive time value for h(t) = 0
It takes about 7.12 seconds for the rocket to crash.
