Question

:) Use the quadratic formula to solve the problem.

A soccer player throws the ball onto the field from the sideline. An equation modeling the ball's flight is h = -16t2 + 18t + 2. In how many seconds will the ball reach the ground?
Choose one answer.
a.
in about 2 seconds

b.
in about 1.2 seconds

c.
in about 1.8 seconds

d.
Cannot be determined

Answer 1

So using your quadratic formula with

-16 for 'a'
18 for 'b'
and
2 for 'c'

plug those into

\[\frac{ -b \pm \sqrt{b^2 - 4ac} }{ 2a }\]

you will get 2 times...1 of which will most likely be negative....but you can ignore that...since we only want the positive number

Answer 2

edit * you will get 2 results!*

Answer 3

yes, the ball touches the ground when h(t)=0.

Answer 4

-4/32 or -1/8 ?

Answer 5

wait thats not even an option

Answer 6

not quite...try that again

the 2 results I get are

1.22 and -.101

Answer 7

john, well done! xp

Answer 8

So how did i not get that. Wtf ugg oh well. Thanks

Answer 9

well no try it again though

\[\frac{ -18\pm \sqrt{18^2 - 4(-16)(2)} }{ 2(-16) }\]

is what you should have done

Answer 10

that is what i did.

Answer 11

there's a \(\pm\) in the formula. it is the "-" that is giving the answer 1.2

Answer 12

so then lets simplify whats under that radical

18² is 324

-4 times -16 times 2 is 128

so now you have

\[\frac{ -18\pm \sqrt{452} }{ -32 }\]

Answer 13

*It's √452 because you add 324 and 128*

Answer 14

so now you evaluate the √452

...which will give you

21.2602916254

so you have 2 equations

\[\frac{ -18 + 21.2602916254 }{ -32 }\]

and

\[\frac{ -18 - 21.2602916254 }{ -32 }\]

Answer 15

so do those out and what are the 2 results you get?

Answer 16

Well...she left...regardless....There's the work :D lol