Question

Arthur drops a ball from a height of 81 feet above the ground. Its height, h, is given by the equation h = –16t2 + 81, where t is the time in seconds. For which interval of time is the height of the ball less than 17 feet?
a. t>2
b. 0 12 years ago

Answer 1

try

Answer 2

only one answer makes any sense so no work is necessary

Answer 3

c?

Answer 4

t=2 is not even an interval

Answer 5

-2<t<2 implies there is such a thing as negative time

Answer 6

ok, d?

Answer 7

0<t<2 implies that the ball starts below 17 feet

Answer 8

17 > -16t^2 + 81

Add 16t^2 on both sides

16t^2 + 17 > 81

Subtract 17 on both sides

16t^2 > 64

Divide 16 on both sides

t^2 > 4

square rooting both sides yield

t > 2 and t < -2, but negative time doesn't make sense in this case which makes the answer a.

Answer 9

no, definitely not D
time does not go backwards

Answer 10

stop guessing and actually try

Answer 11

a