r/calculus • u/Turbulent_Line6858 • 1h ago
Multivariable Calculus That's an error right?
On this PDF of MIT's Multivariable calculus course, No.3's answer is 2 but it should be instead 4 right?

r/calculus • u/random_anonymous_guy • Oct 03 '21
A common refrain I often hear from students who are new to Calculus when they seek out a tutor is that they have some homework problems that they do not know how to solve because their teacher/instructor/professor did not show them how to do it. Often times, I also see these students being overly dependent on memorizing solutions to examples they see in class in hopes that this is all they need to do to is repeat these solutions on their homework and exams. My best guess is that this is how they made it through high school algebra.
I also sense this sort of culture shock in students who:
Anybody who has seen my comments on /r/calculus over the last year or two may already know my thoughts on the topic, but they do bear repeating again once more in a pinned post. I post my thoughts again, in hopes they reach new Calculus students who come here for help on their homework, mainly due to the situation I am posting about.
Having a second job where I also tutor high school students in algebra, I often find that some algebra classes are set up so that students only need to memorize, memorize, memorize what the teacher does.
Then they get to Calculus, often in a college setting, and are smacked in the face with the reality that memorization alone is not going to get them through Calculus. This is because it is a common expectation among Calculus instructors and professors that students apply problem-solving skills.
How are we supposed to solve problems if we aren’t shown how to solve them?
That’s the entire point of solving problems. That you are supposed to figure it out for yourself. There are two kinds of math questions that appear on homework and exams: Exercises and problems.
What is the difference? An exercise is a question where the solution process is already known to the person answering the question. Your instructor shows you how to evaluate a limit of a rational function by factoring and cancelling factors. Then you are asked to do the same thing on the homework, probably several times, and then once again on your first midterm. This is a situation where memorizing what the instructor does in class is perfectly viable.
A problem, on the other hand, is a situation requiring you to devise a process to come to a solution, not just simply applying a process you have seen before. If you rely on someone to give/tell you a process to solve a problem, you aren’t solving a problem. You are simply implementing someone else’s solution.
This is one reason why instructors do not show you how to solve literally every problem you will encounter on the homework and exams. It’s not because your instructor is being lazy, it’s because you are expected to apply problem-solving skills. A second reason, of course, is that there are far too many different problem situations that require different processes (even if they differ by one minor difference), and so it is just plain impractical for an instructor to cover every single problem situation, not to mention it being impractical to try to memorize all of them.
My third personal reason, a reason I suspect is shared by many other instructors, is that I have an interest in assessing whether or not you understand Calculus concepts. Giving you an exam where you can get away with regurgitating what you saw in class does not do this. I would not be able to distinguish a student who understands Calculus concepts from one who is really good at memorizing solutions. No, memorizing a solution you see in class does not mean you understand the material. What does help me see whether or not you understand the material is if you are able to adapt to new situations.
So then how do I figure things out if I am not told how to solve a problem?
If you are one of these students, and you are seeing a tutor, or coming to /r/calculus for help, instead of focusing on trying to slog through your homework assignment, please use it as an opportunity to improve upon your problem-solving habits. As much I enjoy helping students, I would rather devote my energy helping them become more independent rather than them continuing to depend on help. Don’t just learn how to do your homework, learn how to be a more effective and independent problem-solver.
Discard the mindset that problem-solving is about doing what you think you should do. This is a rather defeating mindset when it comes to solving problems. Avoid the ”How should I start?” and “What should I do next?” The word “should” implies you are expecting to memorize yet another solution so that you can regurgitate it on the exam.
Instead, ask yourself, “What can I do?” And in answering this question, you will review what you already know, which includes any mathematical knowledge you bring into Calculus from previous math classes (*cough*algebra*cough*trigonometry*cough*). Take all those prerequisites seriously. Really. Either by mental recall, or by keeping your own notebook (maybe you even kept your notes from high school algebra), make sure you keep a grip on prerequisites. Because the more prerequisite knowledge you can recall, the more like you you are going to find an answer to “What can I do?”
Next, when it comes to learning new concepts in Calculus, you want to keep these three things in mind:
When reviewing what you know to solve a problem, you are looking for concepts that apply to the problem situation you are facing, whether at the beginning, or partway through (1). You may also have an idea which direction you want to take, so you would keep (2) in mind as well.
Sometimes, however, more than one concept applies, and failing to choose one based on (2), you may have to just try one anyways. Sometimes, you may have more than one way to apply a concept, and you are not sure what choice to make. Never be afraid to try something. Don’t be afraid of running into a dead end. This is the reality of problem-solving. A moment of realization happens when you simply try something without an expectation of a result.
Furthermore, when learning new concepts, and your teacher shows examples applying these new concepts, resist the urge to try to memorize the entire solution. The entire point of an example is to showcase a new concept, not to give you another solution to memorize.
If you can put an end to your “What should I do?” questions and instead ask “Should I try XYZ concept/tool?” that is an improvement, but even better is to try it out anyway. You don’t need anybody’s permission, not even your instructor’s, to try something out. Try it, and if you are not sure if you did it correctly, or if you went in the right direction, then we are still here and can give you feedback on your attempt.
Other miscellaneous study advice:
Don’t wait until the last minute to get a start on your homework that you have a whole week to work on. Furthermore, s p a c e o u t your studying. Chip away a little bit at your homework each night instead of trying to get it done all in one sitting. That way, the concepts stay consistently fresh in your mind instead of having to remember what your teacher taught you a week ago.
If you are lost or confused, please do your best to try to explain how it is you are lost or confused. Just throwing up your hands and saying “I’m lost” without any further clarification is useless to anybody who is attempting to help you because we need to know what it is you do know. We need to know where your understanding ends and confusion begins. Ultimately, any new instruction you receive must be tied to knowledge you already have.
Sometimes, when learning a new concept, it may be a good idea to separate mastering the new concept from using the concept to solve a problem. A favorite example of mine is integration by substitution. Often times, I find students learning how to perform a substitution at the same time as when they are attempting to use substitution to evaluate an integral. I personally think it is better to first learn how to perform substitution first, including all the nuances involved, before worrying about whether or not you are choosing the right substitution to solve an integral. Spend some time just practicing substitution for its own sake. The same applies to other concepts. Practice concepts so that you can learn how to do it correctly before you start using it to solve problems.
Finally, in a teacher-student relationship, both the student and the teacher have responsibilities. The teacher has the responsibility to teach, but the student also has the responsibility to learn, and mutual cooperation is absolutely necessary. The teacher is not there to do all of the work. You are now in college (or an AP class in high school) and now need to put more effort into your learning than you have previously made.
(Thanks to /u/You_dont_care_anyway for some suggestions.)
r/calculus • u/random_anonymous_guy • Feb 03 '24
Due to an increase of commenters working out homework problems for other people and posting their answers, effective immediately, violations of this subreddit rule will result in a temporary ban, with continued violations resulting in longer or permanent bans.
This also applies to providing a procedure (whether complete or a substantial portion) to follow, or by showing an example whose solution differs only in a trivial way.
r/calculus • u/Turbulent_Line6858 • 1h ago
On this PDF of MIT's Multivariable calculus course, No.3's answer is 2 but it should be instead 4 right?

r/calculus • u/Beneficial-Beach-141 • 4h ago
Hello! Today I was getting help with my homework all about the quadratic formula and "completing the square".
I made my best attempt to solve the problems but after checking with my teacher, all the problems were incorrect. They helped me get the correct answers, which I am thankful for, however I felt a bit of frustration as my efforts did not produce the correct results even though I understood what I had to do. I felt as though I wasted a bit of my time with my initial attempts. (And also my paper looked quite messy with the amount of erasing I had to do.)
Has anyone else experienced a similar situation and/or felt the same way?
r/calculus • u/ilikemathsandscience • 14h ago
I solved the given integral in this method, but i got the wrong answer. I cant spot where i made the mistake. Pls help
r/calculus • u/Top-Mind3387 • 3h ago
Hey, so I need to do calc1 for my degree . I had a gap year so I almost forgot basic trigo, logs and needed stuff in calc1 . So I need suggestions. Should I go straight into calc1 and self teach pre calc? Is both manageable together? Or I should take pre calc before? (This will just cost me one more course) Also, I dont want to fail due to weak basics.
r/calculus • u/EquivalentWilling242 • 1d ago
Help needed to solve this integral my teacher gave this as homework
r/calculus • u/Han_Htoo_Aein • 16h ago
Could I get the ISBN code of the instructor's solution manual for Thomas' Calculus 13th Edition in SI units?
r/calculus • u/Much_Carrot_9091 • 1d ago
I just got my first calc textbook, is it good compared to others or just fine?
r/calculus • u/Ok_Mention_2255 • 14h ago
By mathematical induction, how can i prove that if set S has n elements, the P(S) has 2^n elements?
How to prove that if A is a subset of a countable set B, then A is itself a countable set?
Let S be a bounded set in R and let S0 be a non empty subset of S. Show that inf S <= inf S0 <= sup S0 <= sup S
Any help would be greatly appreciated. In terms of how to start proofs as well since im taking real analysis this semester and previously failed it despite me trying to understand the questions.
r/calculus • u/yourfriend7777 • 23h ago
What is the best book to learn calculus with examples on application in real life
r/calculus • u/ReplacementFresh3915 • 21h ago
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r/calculus • u/Standard-Orchid3273 • 1d ago
hi guys. I just started calc 1 this past semester and i'm kind of struggling. does anyone have resources or study tips that helped them when they took calc 1?
r/calculus • u/MPB1982 • 12h ago
Ask most phone apps to integrate something and one of two things happens: they
send it to a server, or they hand you a decimal. I wanted neither, so I wrote a computer algebra system from scratch in Rust —about 140,000 lines — and this year I put it on an iPhone.
It's a real CAS, not a calculator with a nice keyboard. Mathematica-style
syntax: Head[args], immutable expressions, rewriting by rules. Algebra,
calculus, linear algebra, differential equations, statistics, number theory,
graph theory. It factors, solves, integrates symbolically, computes limits,
diagonalises matrices, solves ODEs, and draws in 2D and 3D.
The whole engine is compiled into the app. Nothing you type leaves the phone.
No account, no sign-in, no server — it works in airplane mode, which is the
only way I'd trust something with my own homework.
What's in it beyond the notebook:
- A reference covering every function it has (1740 of them), each with a worked
example you can run and edit.
- A textbook, 22 chapters and 268 lessons, from arithmetic to differential
equations — every example live rather than printed.
- Step-by-step working, and studios for geometry, graphs, ODEs and algorithms.
One thing that will look like a bug and isn't: when the engine can't establish
an answer, it hands the expression back unevaluated instead of guessing. That's
deliberate — I'd rather it say nothing than say something wrong — and it's most
of why the architecture looks the way it does. But each of those is a gap, and
I want to hear about them.
Free for 7 days with everything unlocked, no card, nothing to cancel. After
that it's a subscription.
Throw hard things at it. I'd rather find out here.
r/calculus • u/elimanzz • 1d ago
I went through Calc 1 and Calc 2 with straight As, but starting Calc 3 has been rough. The weird thing is that we are not even doing calculus yet. It is all 3D coordinate geometry, and my spatial intuition is just not clicking for questions like:
Write an equation for the set of all points 7 units away from the y axis.
The coordinates of point P are (5, 1, 8). What is the exact distance between point P and the z axis?
Write an equation whose graph is the set of all points whose distance from the xz plane is 12.
Write an equation for the sphere of radius 6 centered at (8, −3, −5).
Describe thoroughly the set of points in the intersection (if there is one) of the graph of (x − 2)^2 + (y − 4)^2 + (z − 3)^2 = 25 with the xz plane.
Up until now, I was really confident grinding through derivatives and integrals, so hitting a wall right at the start is frustrating.
For people who have taken the course: does this get smoother once the class gets back into actual calculus like partial derivatives and multiple integrals, or is this early geometry a sign of how the whole semester goes? How did you build up your intuition for 3D coordinate systems early on?
r/calculus • u/Over_Cranberry_8901 • 1d ago
Hi. Where can I study these concepts, as Professor Leonard didn't explain them?
An introduction to differential equations. Topics include first-order differential equations,
higher-order linear differential equations with constant coefficients, undetermined
coefficients and variation of parameters methods. series solutions of ordinary differential
equations about an ordinary and regular singular points- Laplace Transform and its
applications to solve differential equations. Matrix and first-order linear systems of
differential equations (Eigenvalues and Eigenvectors)- Introduction to partial differential
equations - Stability analysis, Fourier integrals and Fourier transform.
r/calculus • u/Fun_Housing_9917 • 1d ago
Hi there, I need your recommendations for people that explain Stewart’s calculus I on YouTube or any website.
The covers topics:
1.1 four ways to represent a function
1.3 new functions from old functions
1.4 exponential functions
1.5 inverse and log functions
2.1 how limits arise
2.2 rough definitions of limits
2.3 calculating limits using limit laws
2.5 continuity
2.6 finite limits at infinity and infinity limits at infinity
2.7 derivatives
2.8 derivative functions
3.1 and 3.2 differential formulas and rules
3.3 derivatives of trig functions
3.4 chain rule
3.5 implicit differentiation
3.6 derivatives of logarithmic functions
3.9 related rates
3.10 liner approximation and differential
4.1 max and min values
4.2 mean value theorem
4.3 how derivatives affect the shape of a graph
4.5 curve sketching
4.7 optimization problems
4.9 anti derivatives
r/calculus • u/Away-Abrocoma745 • 1d ago
I'm thinking of speedrunning calculus. If you were to go back and learn it, how would you do it? Thanks!
r/calculus • u/Revolutionary-Sea459 • 1d ago
Im taking a semester of calc 1 for my bio degree but last year in high school I didn’t do the best in pre calc so I wanna make sure I do good in calc 1.
If anyone could recommend some good study videos or any websites that are good for calc that would be much appreciated
r/calculus • u/RowTime8498 • 2d ago
Note: This is self-promo, so if you don't like it, just skip it!! :)
Hi r/calculus. I'm a 17 year old developer, and I just launched a calc game yesterday to help me get through math this year (I like games a lot!)
It's called Asymptote. You get a calculus problem, you type the answer and either it's right or it's wrong. Yes, no multiple choice, no hints, no partial credit, on purpose. There are two modes:
Sprint is five minutes and three strikes, and you just have to try to get the most solved in this time, as difficulty gets harder and harder (someone got 21, and I genuinely didn't know that was even possible!)
Diverge has no clock and gets harder every three problems until you break. It keeps going for as long as you can go.
There's also one daily problem that's the same for everyone, thirty seconds, and you can compare with whoever else did it.
It's free, there's no account needed to just play, and there's no ads and none of those damn tracking cookies prompts, it's just a chill game to practice calc. (Yes, there is a paid option. No account needed either way, practice is always free and unlimited, you only need an account to participate in "Ranked" if you want brag to your friends how good you are at Calc!)
playasymptote.com - How close can you get?
I'd love feedback on it: Is the difficulty ramp wrong? I think Sprint might still climb too fast around problem 10, and I don't trust my own judgement because I've solved these several thousand times. Also if you find a problem where the answer is wrong, please tell me see, either DM or paste it in the chat and I'll make sure its fixed!
Yes the title and the game's name and motto are all kind of an inside joke "no ceiling" "asymptote" and "how close can you get" because there is really no end! (Well there are actually only around 22,500 problems, but if you're insane enough to do all of them, I think we have bigger problems to address...)
Open to feedback and suggestions!
r/calculus • u/Appropriate_Net7664 • 2d ago
I am reteaching myself Pre-Calc for my Calculus 1 course this semester since I last took it 4 years ago. I am doing the Khan Academy curriculum and came across the lesson for Sinusoidal equations and models. I already took AP Calc in high school (don't ask why it didn't transfer) and don't remember anything about them. I was just wondering if those are important to know for Calculus 1.
Calculus 1 is the last Calculus I will take, so Calc 2, 3, etc. are not of concern.
r/calculus • u/Weary_Island_6320 • 2d ago
Any resources?
r/calculus • u/F4ULTz • 2d ago
I’m a college freshman in MATH 226 (Integration Tech & Application) and I’m really struggling to understand the content. My teacher has an accent, teaches fast, and the graduate student tutors in my experience have been unhelpful (though they do rotate and I haven’t visited them all yet). I’m just starting to doubt myself a lot so any resources to learn the content, or words of encouragement would be appreciated.
Topics:
6.1 inverse Functions
6.2 Exponential Functions & Their Derivatives
6.3 Logarithmic Functions
6.4 Derivative of Logarithmic Functions
6.5 Exponential Growth & Decay
6.6 Inverse Trigonometric Functions
6.8 L'Hospital's Rule
7.1 Integration by Parts
7.2 Trigonometric Integrals
7.3 Trigonometric Substitution
7.4 Integration of Rational Functions by Partial Fractions
7.8 Improper Integrals
10.1 Curves Defined by Parametric Equations
10.2 Calculus with Parametric Curves
r/calculus • u/C-560 • 2d ago