Question

Question 4 (Multiple Choice Worth 2 points)

If a baseball player hits a baseball from 4 feet off the ground with an initial velocity of 64 feet per second, how long will it take the baseball to hit the ground? Use the equation h = –16t2 + 64t + 4.

2 plus or minus square root of 17 end root over 2

quantity of 2 plus or minus square root of 17 all over 2

2 plus or minus 4 square root of 17

quantity of 16 plus or minus square root of 17 all over 2

Answer 1

Here's what I have:
h=-16t^2+64+4
0=-16t^2+64t+4
0=-4(4t^2-16t-1)

x=-b+-sqrt(b^2-4ac)/2a
x=-(-16)+-sqrt(-16^2-4(4)(-1)/2(4)
x=16+-sqrt(256-4(-4)/8
x=16+-sqrt(256+16)/8
x=16+-sqrt(272)/8
and now I'm stuck... help?

Answer 2

I think the next step would be:
x=16+-sqrt(17)*sqrt(16)/8
then
x=16+-4sqrt(17)/8
??

Answer 3

\[-16t^{2} + 64t + 4 = 0\] would give us
\[t = 2 - \frac{ \sqrt{17} }{ 2 }\] and
\[t = \frac{ 1 }{ 2 }(4+\sqrt{17})\]

Answer 4

So its the second value!

Answer 5

Can you show me how you got that? (: