<p>ohh i see
and if it was the other case, would it be 1?</p>
<p>Yes, infinity/infinity^2 approaches to zero. So, you get 1 because e^0=1.</p>
<p>Thanks again to everyone that responded. I initially thought the answer was E = infinity, but when I turned to the internet I came across a source that said infinity/infinity equals 0, and then I got confused. I went back to my text and realized that hotinpursuit was correct. The answer is infinity.</p>
<p>I have another problem to add to the mix:</p>
<p>If f(x) = 2x + cos2x, then f’(3pi/4) = ?</p>
<p>(A) 0
(B) 1
(C) 2
(D) 3
(E) 4</p>
<p>If f(x) = 2x + cos2x, then f’(3pi/4) = ?</p>
<p>f’(x) = 2 - 2sin(2x)
f’(3pi/4) = 2 - 2*sin (3pi/2) = 4 Answer is E.</p>
<p>I have a question: </p>
<p>For the equations x = sin t and y = (cos t)^2 what is the area under the curve from 0 to pi/2?</p>
<p>A) 1/3
B) 1/2
C) 2/3
D) 1
E)4/3</p>
<p>I do not understand how to combine these…</p>
<p>Use (sin t)^2 + (cos t)^2 = 1. Solve for (cos t)^2 and replace it (it should be 1-(sint t)^2). You know that x = (sin t).</p>
<p>Essentially, y = 1 - x^2. Integrate from 0 to pi/2 (unless you need to convert your limits of integration…I’m not sure about that).</p>
<p>I say C. I believe 0 and pi/2 are the limits for t. If that is the case, x=sin (pi/2)=1 and x=sin(0)=0. So, integrate the function that 314159265 has. That’s is my reasoning and I don’t know if it’s right or not.</p>
<p>Yeah, answer is C.
(sin t)^2 + (cos t)^2 = 1
x^2 + y = 1
y = 1 - x^2
Since it’s a dx problem, limits change to sin 0 (=0) and sin (pi/2) (=1)
integral from 0 to 1 of (1 - x^2) dx = x - x^3 = 2/3</p>
<p>Very nice explanations. Thanks.</p>
<p>Also, in the practice problems I’ve been doing, problems involving Rotating around an Axis to Create a Solid are extremely rare. I do often have trouble figuring out whether to use (R-r)^2 or R^2 - r^2, so I’m wondering if there will be many problems like these on the AP. Any thoughts?</p>
<p>It is pretty likely there will be one on there.</p>
<p>hotinpursuit, I don’t seem to understand your question. Can you elaborate?</p>
<p>i think he means the disk-washer method vs shells, but im not sure</p>
<p>They’re both disk method. The first one is disk method and the second, specifically, is Washer’s Method.</p>
<p>yeah, the first is a curve being rotated around a line of x=r. The second is washer so 2 curves being rotated around a certain line - in that case, the y-axis.</p>
<p>for the FRQ portion of the bc exam, ab and bc sometimes coincide with each other. for the questions that ask to implicity differentiate a function to prove that it equals the function, like prove that dy/dx of (x^2)+4(y^2)=7+3xy is (3y-2x)/(8y-3x), can we do it using partial derivatives (-Fx/Fy) instead of doing it the AB way and differentiating each variable and still get credit? because that would save some time…</p>
<p>You can use more advanced techniques on the AP Calculus exam, but you probably want to make sure that you cite that you’re using partial derivatives, in case some of the graders aren’t familiar with the technique.</p>
<p>I assume the graders want to know how well you know <em>single-varialbe</em> calculus. Sure it’ll save you time, but, just to be on the safe side, I would do it the way the graders would want it done.</p>
<p>Oh alright. Half of the curriculum in calc c is multivariate stuff though. So it should be reasonable imo for graders to be supportive or familiar of those techniques. either way I think I’ll just do it the “long” way in the frqs just to be safe. It wasn’t that significant of a time diference in most cases.</p>
<p>Ah yet another review. This will be sooo helpful 
Hopefully I’ll do better on BC this time than I did with AB sophomore year…</p>
<p>Take the Sparknotes Diagnostic Test for Calc BC(don’t go over the time limit) and post your score.
[SparkNotes:</a> AP Calculus: Test Center](<a href=“http://testprep.sparknotes.com/testcenter/ap/calculus/]SparkNotes:”>http://testprep.sparknotes.com/testcenter/ap/calculus/)
I got 5 questions right out of 35, 8 wrong, rest unanswered…which predicts a 1 on the AP…this is not looking too good…</p>