Question

Derek kicks a soccer ball off the ground and in the air, with an initial velocity of 31 feet per second. Using the formula H(t) = -16t2 + vt + s, what is the maximum height the soccer ball reaches?

14.2 feet
14.6 feet
15.0 feet
15.3 feet

Answer 1

@iGreen , i got 15.0 but im not sure. can you explain this all out?

Answer 2

You have to find the vertex again.

Answer 3

Well to be more specific, you have to find the x-value of the vertex.

You can use this formula:

\(\dfrac{-b}{2a}\)

Here, our function is in the form of \(ax^2 + bx + c\)

Answer 4

Therefore our points are:

a = -16

b = 31

31 is from the velocity.

\(\dfrac{-b}{2a}\)

\(\dfrac{-31}{2(-16)}\)

\(\dfrac{-31}{-32}\)

Can you divide that?

Answer 5

Actually..we have to find the y-value of the vertex..lol.

Answer 6

Divide -31 / -32. @SouthernRebel101

Answer 7

@SouthernRebel101 Are you there?

Answer 8

sorry @iGreen was away from computer people showed up at my door

Answer 9

Okay, can you divide -31 / -32?

Answer 10

i got 0.96875

Answer 11

@iGreen

Answer 12

Yep, now we can plug this back in to find the y-value:

H(t) = -16t^2 + 31t

H(t) = -16(0.97)^2 + 31(0.97)

H(t) = -16(0.9409) + 30.07

H(t) = -15.0544 + 30.07

Can you add that? @SouthernRebel101

Answer 13

all of them added up?

Answer 14

@iGreen

Answer 15

Just add -15.0544 + 30.07

Answer 16

i got 45.1244 @iGreen

Answer 17

That's -15.0544, not positive.

Answer 18

oh, oops did not see that one seocnd

Answer 19

15.0156, so was i right? C? @iGreen

Answer 20

Yep, C is right.

Answer 21

:D YAY! thankyou so much

Answer 22

Np.