Question

David kicks a soccer ball off the ground and in the air, with an initial velocity of 35 feet per second. Using the formula
H(t)=-16t^2+vt+s, what is the maximum height the soccer ball reaches?
A. 17.9 feet
B. 18.2 feet
C. 18.7 feet
D. 19.1 feet

Please help, I have more than one question like this and it's a module test, so I can't get it wrong. I don't understand how to do this at all.

Answer 1

v is supposed to be the initial speed of 35 and s is the initial height which is 0, so the equation is \[h(t)=-16t^2+35t\], but that won't work with your options.

Answer 2

at height 0
-16t^2 - 35t = 0

- we can convert this to vertex form and find maximum height

Answer 3

@peachpi I still don't understand what I would do after getting that equation, because the one I had was the exact same but I had + s on the end. But what would I do next after getting h(t)=-16t^2+35t?

Answer 4

* -16t^2 + 35t = 0

Answer 5

@welshfella would I do -16t^2=0 and -35t=0 now or is that completely wrong

Answer 6

Hi @brunsonnie use this, this might help

https://mathway.com/

Answer 7

You could do t = -b/(2a) to find the time of the max height.
t = -35/(2*-16)
Then plug that in for the height

Answer 8

take out -16
-16[t^2 + 2.1875]
= -16[(x - 1.09375)^2 - 1.1964]

maxm height = 16 * 1.1964 = 19.14

Answer 9

* thats t not x!

Answer 10

the 1.1964 comes fro 1.09375^2

Answer 11

Thanks

Answer 12

yw