Question 1193392
.
For numbers 6: Elaine shoots an arrow upward at a speed of 32 feet per second
from a bridge that is 28 feet high. The height of the arrow is given by the function h(t) =
-16t2 + 32t + 28, where t is the time in seconds.
How long would it take before the arrow reached the ground?
~~~~~~~~~~~~~~~


<pre>
To answer this question, you need to solve equation h(t) = 0,  which is

    -16t^2 + 32t + 28= 0.


Simplify it by dividing both sides by -4

    4t^2 - 8t - 7 = 0,


then apply the quadratic formula 

    {{{t[1,2]}}} = {{{(8 +- sqrt(8^2 + 4*4*7))/(2*4)}}} = {{{(8 +- sqrt(176))/8}}} = {{{(8 +- 4*sqrt(11))/8}}} = {{{1 + 0.5*sqrt(11)}}}.


Of the two roots, reject the negative one and accept the positive value.


<U>ANSWER</U>.  The arrow will reach the groind in {{{1 + 0.5*sqrt(11)}}} = 2.66 seconds (rounded).    <U>ANSWER</U>
</pre>

Solved.


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In this site, &nbsp;there is a bunch of lessons on a projectile thrown/shot/launched vertically up


&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/travel/Problem-on-a-projectile-moving-vertically.lesson>Problem on a projectile moving vertically up and down</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/travel/Problem-on-projectile-shooted-vertically-upward.lesson>Problem on an arrow shot vertically upward</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/travel/Typical-problems-on-an-projectile-moving-vertically-up-and-down.lesson>Problem on a ball thrown vertically up from the top of a tower</A> 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/travel/Problem-on-a-toy-rocket-launched-vertically-up--from-the-top-of-a-platform.lesson>Problem on a toy rocket launched vertically up from a tall platform</A>


Consider these lessons as your textbook, &nbsp;handbook, &nbsp;tutorials and &nbsp;(free of charge) &nbsp;home teacher.
Read them attentively and learn on how to solve this type of problems once and for all.


Also, &nbsp;you have this free of charge online textbook in ALGEBRA-I in this site

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson>ALGEBRA-I - YOUR ONLINE TEXTBOOK</A>.


The referred lessons are the part of this textbook under the topic "<U>Projectiles launched/thrown and moving vertically up and dawn</U>".



Save the link to this online textbook together with its description


Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson


to your archive and use it when it is needed.