Rui wants opinions: Why is perms and combs so ****?

[RuiAce]

Hey everyone

Okay, so I know that a lot of people hate this topic. And not gonna lie, I once hated it too; ESPECIALLY during the HSC. It was certainly worse in 4U compared to 3U as well. And then first year uni happened and now it's one of my favourite things in maths - I'm probably gonna be researching it soon! Since then, I've pretty much forgotten why I hated this topic so much in high school. So I'm basically asking all of you who do 3U or above (or equivalent):

What makes permutations and combinations so loathsome?

As far as this goes, I'm mainly asking for self interest. I may choose to act on some of the opinions and see if there's a way I can make this topic easier to understand. But if I do, I want to know why it tends to cause students struggle/grievance and why it's so despised. It's actually something so beautiful, but something definitely is not right about it as far as the HSC goes.

Appreciate any input! I would really prefer if I have a mix of responses between ex-HSC students and current HSC students, as well as mods and non-mods!

This thread has been temporarily stickied. The sticky will be removed in due time.

[Natasha.97]

Perms and combs... other than binomial theorem, this is probably the hardest topic in 3U.

- It's quite hard to get your head around questions and what they are actually asking you to find
- Questions involving the greatest coefficient are the hardest imo
- Confusion about when to use nPr and when to use nCr

[Opengangs]

I think it's because perms and combs, like probability, is vastly different to any of the other topics that are taught at high school level. It requires rigorous thinking with approaching each question, and so there's no 'real way' to really study it. While a lot of the other topics are heavy on algebraic manipulation, perms, combs and probability are heavy on analytical thinking, so this makes the whole topic a lot more difficult compared to others.

Needless to say though, I actually love the permutations and combinations topic. It's actually one of my strongest topics out of the whole 3u course, and the 4u (even if I don't do 4u) questions aren't too bad, to me.

[RuiAce]

- Questions involving the greatest coefficient are the hardest imo

Ironically, this thing (which IS binomial theorem, not perms/combs) hasn't been examined since 1988 or something

[Natasha.97]

Ironically, this thing (which IS binomial theorem, not perms/combs) hasn't been examined since 1988 or something

oops, slightly rusty on the particular contents of each topic :3

[beatroot]

As a former 3U student, I strangely found perms and combs easy compared to the other topics. Maybe because I particularly enjoyed probability in Year 10 so that's why I found this particular topic so interesting. It didn't require trig, sketching graphs, calculus etc, you know the usual things that we are used to in Maths. This was actually the first topic that I learnt in 3U in Year 11 so maybe that's why it's memorable. But I did drop 3U for a reason, I was terrible at the other topics. I really don't have a say on Year 12 perms and combs (I'm assuming it's difficult from what my friends and what people on this thread say).

[pikachu975]

Maybe some different interpretations of questions... but imo projectile is the hardest followed by binomial

[chelseam]

Maybe some different interpretations of questions... but imo projectile is the hardest followed by binomial

I think so too! I haven't finished perms & combs yet, and although it might be a bit hard to figure out when to use nPr or nCr, I think it's also the fact that the questions are so different to pretty much the rest of the course because the wording could trip you up if you miss a small detail or don't apply it properly to find the answer!

[Sine]

It is hard and annoying if you learn it out of a textbook or from a teacher, but if you learn from first principles i.e. logic  there shouldn't be any real problems.

remember that most of  the answers to these quesitons can be achieved by using common sense and not just plugging stuff into formulas.

[RuiAce]

It is hard and annoying if you learn it out of a textbook or from a teacher, but if you learn from first principles i.e. logic  there shouldn't be any real problems.

remember that most of  the answers to these quesitons can be achieved by using common sense and not just plugging stuff into formulas.

Actually, whilst you're not wrong, I plug into formulas about as much as I use common sense tbh lol

[Sine]

Actually, whilst you're not wrong, I plug into formulas about as much as I use common sense tbh lol

yeah just do whatever you want on the first go and when you want to check your answer do the other method.

I tend to use the formulas (and sometimes writing out complete sentences to justify stuff) just because it makes marking so much easier for whoever does it.

[EEEEEEP]

It is hard and annoying if you learn it out of a textbook or from a teacher, but if you learn from first principles i.e. logic  there shouldn't be any real problems.

remember that most of  the answers to these quesitons can be achieved by using common sense and not just plugging stuff into formulas.

I think it involves both formulas and logic.

When I did 3 unit maths, formulas were easy enough for it... the logic was what I could not wrap my head around.  Questions aren't as simple as "differentiate this" or graph this", it took some sort of wrapping around where you understood the logic.

[RuiAce]

Unstickied now, but still welcoming opinions!

Interesting stuff up above.

(Although, I definitely did NOT like it anywhere as much as I do now, back in high school.)

[kiwiberry]

I feel like it's a case of whether you can 'see it' or not, especially with the 4u ones - practice can only help to some extent. Sometimes it's hard to interpret the wording of the question, and I've often made mistakes because I missed the word 'identical' or another small detail which is super annoying

[pikachu975]

I feel like it's a case of whether you can 'see it' or not, especially with the 4u ones - practice can only help to some extent. Sometimes it's hard to interpret the wording of the question, and I've often made mistakes because I missed the word 'identical' or another small detail which is super annoying

Yeah and some of the wording is so bad honestly like you interpret the question one way then the answers do it a different way due to the ambiguous wording.