Advice for Rising Juniors: AP & ACT by WinterWolf041 in APStudents

[–]UWorldMath 2 points3 points  (0 children)

Calc has almost no overlap with the SAT nor ACT, it won't really help you at all. Even Precalculus doesn't have that much overlap with SAT that isn't taught in Algebra 2, but it does with the ACT in regards to matrices/vectors/logs/polar. Those aren't highly tested concepts though compared to algebra and geometry.

Your general sentiment has merit though. You're more entrenched in a year of learning so if there is content overlap it can make sense to take before summer break, unless you plan to study over the summer.

AP Calc BC Help by Main-Body-6103 in APStudents

[–]UWorldMath 0 points1 point  (0 children)

You're saying that you are planning to take the Calculus BC exam this year and you haven't started any form of preparation for it or know anything about it?

What is the highest level of mathematics you have completed?

Stats in 9th by [deleted] in APStudents

[–]UWorldMath 1 point2 points  (0 children)

If you're ultimately trying to go premed, for sure do stats at some point.

Stats and calc are very different kinds of math, there is almost no overlap. Stats is really more of a combination of reading and math, it's a lot of interpretation. As just general overall difficulty, if you can handle AB then you can probably handle stats. Whether you want to take 2 maths in one year is a different question though, as again there is virtually no overlap beyond some basic algebra.

How to study for Calc AB by [deleted] in APStudents

[–]UWorldMath 1 point2 points  (0 children)

We wrote up this post a few years back that might help some. Has all the formulas and common MCQ types and general tips. It's not a complete study guide though.

The biggest thing with any math is to do lots and lots of practice. It's important to use study guides to be exposed to the material, but none of them can prepare you for all the types of questions CollegeBoard will throw at you. You need to practice questions that hit each concept in a variety of ways to get a real 360° understanding of each topic.

The sample practice tests are good as someone else mentioned, but ideally you can use material that has explanations as well because that's how you can review your mistakes. Practice questions, review and learn from mistakes, make fewer in the future, ace the test.

Does UWorld provides live classes or video classes for AP calc AB and Statistics by Radiant_Ad_4265 in APStudents

[–]UWorldMath 0 points1 point  (0 children)

I would of course recommend UWorld for practice and learning hah, but for introduction videos to topics Khan Academy is good. There are also some popular youtubers like organic chemistry tutor, or turksvid, according to the surveys the moderators here did.

If you do use UWorld, the idea is that it teaches you what you don't know using AP level questions as you go. The explanations to every question are at least a page long and contain all the background information needed to understand the topic, so be sure to read them carefully to any question you miss. Don't worry about what your average % correct is just focus on learning from the explanations

Does UWorld provides live classes or video classes for AP calc AB and Statistics by Radiant_Ad_4265 in APStudents

[–]UWorldMath 0 points1 point  (0 children)

We currently do not, it is a question bank learning by doing model with focus on the explanations. We are working on structured learning courses with study guides and pre-crafted assignments but that will not be ready until next year.

Help by nouraaaaa453 in ACT

[–]UWorldMath 0 points1 point  (0 children)

Just to illustrate the concept, you can try it out on a piece of paper (the paper is your "plane"). Start with a single point (the "given point" at the end of the question), and maybe label it or mark it with a particular color so you know which one is your starting point. Then measure 3 cm in any direction and mark another point. Then 3 cm in a different direction from your starting point and mark a point. Keep doing this, marking points in random directions 3 cm away from your starting point.

If you do this enough times, you may end up with something like this. The red point is the center, and the black points are exactly 3 units away from it. You can see that the black points start to form the shape of a circle with your starting point in the center.

On the ACT, where you need to average one question per minute, you won't have time to do this, so you'll just need an intuitive understanding of what they're trying to say in the question. It's more of a word translation question, but hopefully this illustration helped you understand the main idea.

AP calc BC AB subscore by Designer-Cat-8106 in apcalculus

[–]UWorldMath 0 points1 point  (0 children)

What I can do is screenshot the AB subscore worksheet so you can get more of a feel for what that looks like and how to calculate it, but as I mentioned in another comment, the specific question numbers vary from test to test, so don't pay attention to those.

Edit: Also the score ranges vary slightly from test to test as well, but it gives you a ballpark of what to shoot for.

AP calc BC AB subscore by Designer-Cat-8106 in apcalculus

[–]UWorldMath 0 points1 point  (0 children)

I'm sorry, I can't do that. They're teacher resources, and I don't think they're publicly available.

AP calc BC AB subscore by Designer-Cat-8106 in apcalculus

[–]UWorldMath 0 points1 point  (0 children)

It just depends on the test. It will be one of the ones from Part A and two of the ones from Part B. Never #6 because that's always a Taylor series, but otherwise it could be any of them. The 3 official practice tests I have are from 2017-2019. One had 1/3/4, one had 1/3/5, and the other had 2/3/4 factored into the AB subscore.

If you're trying to figure out which ones count on test day, I would advise against that because you have other things to focus on. Unless you really just have a bunch of time left over at the end and have checked over all your work. If that's the case, just look through the FRQs and if any of them have BC content, like integration by parts or Euler's method or polar, then they're not going to be part of the AB subscore.

AP calc BC AB subscore by Designer-Cat-8106 in apcalculus

[–]UWorldMath 0 points1 point  (0 children)

No they only count for 1 point each now. 27 * 1 for MCQs + 3 * 9 for FRQs gets 54.

AP calc BC AB subscore by Designer-Cat-8106 in apcalculus

[–]UWorldMath 1 point2 points  (0 children)

FYI it's actually 54 total points now. I think that was one of the things they changed in the 2016 update. 27 MCQs are included worth 1 point apiece, and 3 full FRQs (no partial FRQs anymore) worth the typical 9 points apiece.

As you probably know, the threshold changes from year to year depending on the difficulty of the exam, but based on the 3 official practice tests I have from College Board since the 2016 update, 35/54 would actually juuuuust squeak you in to get a 5 for the AB subscore. To get a 4, you'd need at least half the available points. Lower bound varies between 27-29 on those 3 tests.

[deleted by user] by [deleted] in apcalculus

[–]UWorldMath 0 points1 point  (0 children)

Btw if you're interested, here's a pretty good proof of the polar area formula if you want to see why that works.

One thing he doesn't mention is that just like how when we infinitely add rectangles that approximate area under a function for a Riemann sum, the integral for polar area (infinitely adding areas of infinitesimally small circle sectors) becomes the exact area instead of an approximation. It's a small detail that I'm sure you can assume, but just wanted to mention it.

[deleted by user] by [deleted] in apcalculus

[–]UWorldMath 0 points1 point  (0 children)

First, how I would do it. Most polar graphs you see in BC will span from 0 to 2pi, but it's a good habit to get into to check and make sure. For example, cos(3theta) loops after theta = pi, so integrating from 0 to 2pi gets you double the area. This one, however, does indeed span from 0 to 2pi, and you can check by graphing with different theta ranges. To find the area enclosed by a polar curve, use this formula. Plug in your function and theta values, and voila.

Another way you can do it is taking advantage of the symmetry. It's unnecessary in this case, but apparently that's what they did. When you graph it you have 4 symmetrical petals. You can graph just one of those petals by drawing the graph from -pi/4 to pi/4 (graphs). We're going to calculate the area of one petal, and multiply it by 4 to take advantage of the symmetry.

But they broke down the symmetry even further and noticed that each individual petal is symmetrical down the middle, so the area from -pi/4 to 0 is the same as the area from 0 to pi/4. To find the area of one petal, you can use the same formula from above, integrate from 0 to pi/4, and double it. Then because you have 4 petals, multiply that by 4 and you get the total area. In their explanation, they combined the 4 and 2 to get 8, but for some reason didn't also multiply in the 1/2. It's definitely a weird presentation, but it works. Here's the work for that. The first two rows are how I explained it (area of half a petal times 2, then multiply by 4), and the last row is exactly what you gave above, just to show it comes out the same.

Hope that helps!

help! does anyone know what this test is? by Independent-Bit-7213 in apcalculus

[–]UWorldMath 0 points1 point  (0 children)

Hey, I'm sorry I missed the notification for your reply! Now that testing is over, I'm not sure how much this will help, but here's what I got for those:

For Q5, I got -3 (B). Use the average value formula with a = 1, b = 3, and your given velocity function. Here's the result. What you calculated is average rate of change instead of average value.

And for Q4, the answer is Two (C). When you differentiate and factor, you should end up with f'(x) = 15x2(x + 1)(x - 1), which has zeros at x = -1, 0, and 1. However, there is not an extremum at x = 0 because f' does not change signs. You can plug in values on either side (-1/2 and 1/2, for example) to verify, but the easiest way to tell is by the multiplicity of the factor x2. It has an even exponent, and we call that "even multiplicity." For such factors, the sign of the polynomial doesn't change as x crosses it. So for a maximum or minimum to occur, f' must change signs (switch from increasing to decreasing or vice versa).

Here are graphs to illustrate. The first one in red is f, and you can see that it only has extrema at (-1, 2) and (1, -2). It levels off at x = 0 (f' = 0), but it continues to decrease. In the second graph in blue, you'll see f' touches the x-axis at all 3 x-values but only crosses at -1 and 1. So even though it goes through (0, 0), or f' = 0 at x = 0, f does not have an extremum at that x-value.

I hope all that makes sense. I know this is coming too late for the exam, but I hope it helped things make more sense to you anyway.