Question

Quadratics?

Answer 1

A model rocket is launched with an initial upward velocity of
235/fts The rocket's height h (in feet) after t seconds is given by the following.
= h−235t16t2
Find all values of t for which the rocket's height is 151 feet.

Answer 2

h=235t - 16 t^2

I just need help getting through it. Could someone show me how to do this?

Answer 3

Find all values of t for which the rocket's height is 151 feet. this means find the values of t when h = 151

Answer 4

if you rearrange the equation to the standard form ax^2 + bx + c = 0 it might help

Answer 5

151= 16t^2+235t
So I'd need to move 151 over to make it c?

@triciaal

Answer 6

yes

Answer 7

a = -16

Answer 8

What will your equation look like in quadratic form if you subtract -151 from both sides of your equation, @Ashley10116 ?

Answer 9

-16t^2 +235t-151 ?

Answer 10

before you do this problem please verify the original equation

Answer 11

Nevermidn, i was wrong.

Answer 12

\(\color{blue}{\text{Originally Posted by}}\) @Ashley10116
A model rocket is launched with an initial upward velocity of
235/fts The rocket's height h (in feet) after t seconds is given by the following.
= h−235t16t2
Find all values of t for which the rocket's height is 151 feet.
\(\color{blue}{\text{End of Quote}}\)
\(\color{blue}{\text{Originally Posted by}}\) @Ashley10116
h=235t - 16 t^2

I just need help getting through it. Could someone show me how to do this?
\(\color{blue}{\text{End of Quote}}\)
Was your original equation \(0=h-235t+16t^2\) or \(h=235t-16t^2\)?

Answer 13

\(0=h-235t+16t^2 \implies -h=-235t+16t^2 \implies h=235t-16t^2\) makes sense, if this is what you were trying to do

Answer 14

I'm a bit confused.

Answer 15

And from there you found \(h=151\) so you substituted it in, and got : \(151=235t-16t^2 \implies -16t^2 +235t-151=0\)

Is this what you had done?

Answer 16

could you please post your original problem by using the drawing tool, or posting the attachment s I could verify you have the correct equation?

Answer 17

Yes, one moment.

Answer 18

@Jhannybean

Answer 19

A model rocket is launched with an initial upward velocity of 235/fts. The rocket's height (h) (in feet) after 't' seconds is given by the following.

h= 235t - 16t^2

Find all the values for t which the rocket's height is 151 in feet.

Round your answer to the nearest hundredth.
There may be more than one answer.

Answer 20

Alright :)

Answer 21

so as @triciaal mentioned earlier, they give you the height, \(h=151\)

Answer 22

Ok. so -16t^2 +235t - 151

Answer 23

There you go.

Answer 24

Now you can plug it into the quadratic formula to find your value(s) of t, or use the completing the square method. quadratic function: \[t=\frac{-b\pm\sqrt{b^2-4ac}}{2a}\]

Answer 25

\[a=-16~,~ b = 235~, ~ c = -151\]

Answer 26

There is also the completing the square method. I will show you how to work the problem using this method and then explain how it's done.

Answer 27

Thank you.

Answer 28

\[-16t^2 +235t-151=0\]\[-16\left(t^2 +\frac{235}{-16}t\right)-151=0\]\[-16\left(t^2-\frac{235}{16}t+\frac{55225}{1024}\right) - 151 - \frac{55225}{64}=0\]\[-16\left(t-\frac{235}{32}\right)^2 -\frac{45561}{64}=0\]Well.. this isn't looking very pretty atm.

Answer 29

That's when we resort to the quadratic formula :P

Answer 30

The -b +- square root of ___ 4-ac formula?

Answer 31

Yes