2012 AP Calculus AB Test Discussion

<p>I’m sure it’s fine especially if it’s the right answer then there is nothing else he could confuse it for. I put ccup and ccdown for my answers</p>

<p>Liam, it was 52… It was asking for instantaneous velocity</p>

<p>I don’t understand how people are getting -ln(81) as their constant for the one FRQ… If I remember correctly it was -ln(100-B) = t/5 + C, and B(0) = 20 (or something like that), so it would be -ln(80), no?</p>

<p>Overall though, the test was pretty easy.</p>

<p>Coming from someone who did absolutely 0 studying for this exam, I found the no-calculator MC section incredibly easy. All of the questions seemed really straightforward, but it probably helped that I was in the mindset that I was going to get a 1…</p>

<p>The with calculator MC questions sucked, though. My N-spire broke last week, so I borrowed my teacher’s for the exam…this one decided to send back every integral that I typed in exactly as I put it in, and not evaluate a thing. I ended up graphing everything, and got kind of flustered. Still, the questions were much more involved than the previous section.</p>

<p>The FRQs killed me. By the time that they came around, half of my classmates literally had their heads down asleep, and I felt the same way. These questions were nothing like the ones that we’ve done in class, which really sucked. They seemed really simple, but I was prepared for something like related rates, a trash truck problem (I don’t remember the name…the one from last year), or more rotation and area stuff. </p>

<p>I just didn’t know what to make of the FRQs…I’m surprised that you all found them easy. The no-calculator section took an eternity for me, and I ended up jumping around from question to question in the last 5 minutes to try to get stuff done.</p>

<p>Question: I saved the first no-calc. question for last, and ended up scribbling a guess. Was g(x)=F(x), and g’(x)=f(x)? I can’t really ask this in a subtle way, and I don’t really remember the letters, either…</p>

<p>@FastNeutrino </p>

<p>That’s what I got, too. </p>

<p>Was the question asking for it in terms of the “y” variable (forget which it was). And if so, were we supposed to e^x it all, to get rid of the LNs??</p>

<p>The question I was talking was the last part of 4, where we had to integrate sqr (25-x^2). And i just realized I divided wrong -_- . I got something along the lines of -248/6, which i thought was -42. And that fraction might be wrong in itself.</p>

<p>Yeah. I got B(t) = 100 - 80e^(-t/5). Not sure why I remember it so clearly. XD</p>

<p>Mada on that third free response you found g’(x) did = f(x) to find g(x) though you had to find the integral of f from 1 (I believe might have been two) so for example if you were looking for g(0) you would have had to subtract the area between 0 and 1 on f(x) so you were close you probably got all the parts on that question except for a.</p>

<p>That’s what I got. Pretty sure it’s right.
BioGen, the question was to integrate xsqrt(25-x^2) from 0 to 5. The answer was 125/3; you had to use u-substitution.</p>

<p>If I put x as a variable instead of t, will I get points off???</p>

<p>You might lose a point. Nothing major though.</p>

<p>You def don’t have to use usub to get 125/3 for the integral of x(25-x^2)^(1/2) from 0 to 5 while it’s a good idea to do something like that so that you get some credit if you mess up you can clearly look at that and tell that it integrates to -1/3(25-x^2)^(3/2) no usub required</p>

<p>What do you guys think the curve will be? I have a feeling it will be on the high end this year. I think I missed 10-15 MC, ahhhhhh. FRQ was pretty simple, although I got confused on the area one, and I don’t think I did very well on the bird question. The cutoff for a 5 shouldn’t go above 70, right? I hope not.</p>

<p>You don’t have to, but to get full credit I chose to.</p>

<p>Did the area problem have two integrals in every answer?</p>

<p>@lilacphrogee: You can’t take the square root of a term with addition or subtraction.</p>

<p>Type the equation into your calculator</p>

<p>great…yet another one that ive missed. i cant believe how dumb i am</p>

<p>Ok, I see where I went wrong. I set up the U-sub right, but evaluated wrong. Hooray /sarcasm. By the way, how did you guys set up the last part of question 2 on the Calculator section, the one where the horizontal line y=k divides the area into two equal parts?</p>

<p>Don’t stress about it, the calc curve is very generous</p>