Question

Help for a medal?

Answer 1

A firecracker shoots up from a hill 160 feet high, with an initial speed of 90 feet per second. Using the formula H(t) = -16t2 + vt + s, approximately how long will it take the firecracker to hit the ground?

Answer 2

Are there any options with this question?

Answer 3

Yeah, the options are

Five seconds
Six seconds
Seven seconds
Eight seconds

Answer 4

Okay, I can try and help you(:

Answer 5

By the way, I'm still here I'm just working on solving it so I can help you.

Answer 6

Alright

Answer 7

Multiply out everything, then move everything over to the right except for "y". If you get something in the form of y = ax^2 + bx + c, where 'a' is not zero, then it's a quadratic equation.

2) Multiply out the right until you get something in the form of y = ax^2 + bx + c, then look at what 'a' would be.

3) y = ax^2 + bx + c is going to be the graph of a parabola. If a > 0, then it opens upwards and the vertex shows the minimum value for y. If a < 0, then it opens downwards, and the vertex shows the maximum value for y.

4) Subtract 24x from both sides, then factor out 8x.

5) See #4

Answer 8

Why delete it? I was in the middle of reading it D:

Answer 9

i made a typo lol

Answer 10

\[\large \text{A firecracker shoots up from a hill } {\color{red}{\text{160 feet high}}},\\
\large\text{with an }{\color{green}{\text{initial speed of 90 feet per second}}}.\\
\large \text{Using the formula } H(t) = -16t^2 + vt + s,\\
\large \text{approximately how long will it take the firecracker to hit the ground?}\]


From that info, we can pull out

\[\large \text{Initial Height: }{\color{red}{ s = 160}}\]
\[\large \text{Initial Velocity: }{\color{green}{ v = 90}}\]


So the expression
\[\large -16t^2 + {\color{green}{v}}t + {\color{red}{s}}\]
turns into
\[\large -16t^2 + {\color{green}{90}}t + {\color{red}{160}}\]
Hopefully this is making sense so far?

Answer 11

but it's fixed now

Answer 12

From here you need to solve
\[\Large -16t^2 + 90t + 160=0\]
for t. Use the quadratic formula to do so

Answer 13

Alright, I can handle it from here. Sorry for the delay, the pizza man came :D

Answer 14

That's ok. Let me know what solutions for t you get.

Answer 15

If I remember too then I will!