<p>Ok, its question number 6 on this website
link: <a href="http://sullivan-math.com/frq2.pdf%5B/url%5D">http://sullivan-math.com/frq2.pdf</a></p>
<p>my answers are:
(a) v = -34e^(-2t)-16
(b) -16 ft/s
(c) t = 1.07s</p>
<p>those answers are correct. of course you could always check part a) by differentiation ;).</p>
<p>^thanks man...
this was a practice question my calc teacher gave me for hw today, and she said the question was VERY TRICKY...and VERY CHALLENGING...I solved it in like 5-minutes, so I got scared that I did something wrong...just goes to show that my calc teacher doesn't know what the f she is doing...</p>
<p>when we were learning derivatives she told us that y = ln(x) was "un-differentiable"....NO JOKE</p>
<p>heh I thought it was the least annoying of the calc BC 97 questions.</p>
<p>That was both an AB and a BC question. The average AB score that year was 1.19 and it was the lowest question average on the BC exam that year as well.</p>
<p>So at least with regards to this question, a lot of folks struggle with it.</p>
<p>The biggest problem is that people didn't know how to separate the variables. A lot of people tried moving just the 2v or just the 32, but not both together. A lot of people also seemed to be thrown off by the absence of a term with t in it.</p>
<p>The problem is that most of the people who couldn't separate the variables properly were pretty much doomed to 0 or 1 out of 9.</p>
<p>wow i feel dumb i keep messing up the last part when i set 20 equal to the equation. somehow i am not getting the same answer. Im not sure if im doing it wrong, can someone plz tell me how to do part c. thanks</p>
<p>note that they ask for speed, since v(t) = -34e^(-2t)-16 or -(34e^(-2t)+16), speed = |v(t)| = 34e^(-2t)+16 = 20 => e^(-2t) = 2/17. Take the natural log of both sides to get -2t = ln(2/17) => t = (ln(17) - ln(2))/2 which is approx. 1.070</p>
<p>Ah, now i understand it. Thanks a lot.</p>