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March 28, 2024, 08:18:28 pm

Author Topic: 3U Maths Question Thread  (Read 1230174 times)  Share 

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RuiAce

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Re: 3U Maths Question Thread
« Reply #690 on: September 26, 2016, 09:52:26 pm »
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That makes sense, thank you!!

Also, could you please explain how to do 13a)iii) from the 2015 hsc paper?

Mod edit: You're most welcome, but please stick to editing prior posts in these situations over unnecessarily posting






lha

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Re: 3U Maths Question Thread
« Reply #691 on: September 26, 2016, 10:00:49 pm »
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How do you do question 14c)iii)?

Btw sorry for all the questions!
« Last Edit: September 26, 2016, 10:24:37 pm by lha »

RuiAce

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Re: 3U Maths Question Thread
« Reply #692 on: September 26, 2016, 10:04:14 pm »
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I only understand how you got c=5 but not the rest. How did you find a=2 and what n equals to?

Also im not sure how to edit my previous posts
There's a modify button in the top right corner of every post you make. Just use that and you're all good.

If the endpoints are 3 and 7 then the distance between the endpoints is 4. But the amplitude is the distance between an endpoint and the centre of motion. So a = 2


Just sub in x=5, v2=11 and you can find n.
i.e. you find n LAST.

IkeaandOfficeworks

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Re: 3U Maths Question Thread
« Reply #693 on: September 30, 2016, 04:14:16 pm »
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Hi guys! Can you help me with this question? Thanks!

jakesilove

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Re: 3U Maths Question Thread
« Reply #694 on: September 30, 2016, 04:55:41 pm »
+1
Hi guys! Can you help me with this question? Thanks!

Hey! Check out what I did below; essentially, I knew I needed to pop out the sinh/h, and the rest works out easily!



Jake
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IkeaandOfficeworks

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Re: 3U Maths Question Thread
« Reply #695 on: September 30, 2016, 05:18:35 pm »
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Thanks! I thought I needed to expand the cos(x+h) so I got confused.    :-X

jakesilove

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Re: 3U Maths Question Thread
« Reply #696 on: September 30, 2016, 05:31:58 pm »
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Thanks! I thought I needed to expand the cos(x+h) so I got confused.    :-X

Totally fair enough. Basically, if you CAN let h equal zero, then you just do. We needed to get rid of the h in the denominator, so we don't divide by zero, but after that we have no problems!
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IkeaandOfficeworks

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Re: 3U Maths Question Thread
« Reply #697 on: September 30, 2016, 06:02:38 pm »
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What about this question? I'm a bit confused on  how to take the theta out. Thanks!

RuiAce

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3U Maths Question Thread
« Reply #698 on: September 30, 2016, 06:06:24 pm »
+1
What about this question? I'm a bit confused on  how to take the theta out. Thanks!


It's actually like the question above it. Just remember to be careful with the fraction
« Last Edit: September 30, 2016, 06:18:11 pm by RuiAce »

samuels1999

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Re: 3U Maths Question Thread
« Reply #699 on: September 30, 2016, 08:59:41 pm »
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Hi Jake,

I am doing Extension 1 mathematics next year, as I did really well in prelim Ext 1. The thing is, I have heard many rumours from students in the year above me that it is really hard to do Extension 1 by itself (without Ext 2). However they say, it's really easy for people doing Extension 2. I just wanted to know what your take on that is (how true is the statement?) and whether extension 1 is really worth doing as it only counts for a single unit in my case.

Thanks heaps,
Samuel
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jakesilove

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Re: 3U Maths Question Thread
« Reply #700 on: September 30, 2016, 09:07:37 pm »
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Hi Jake,

I am doing Extension 1 mathematics next year, as I did really well in prelim Ext 1. The thing is, I have heard many rumours from students in the year above me that it is really hard to do Extension 1 by itself (without Ext 2). However they say, it's really easy for people doing Extension 2. I just wanted to know what your take on that is (how true is the statement?) and whether extension 1 is really worth doing as it only counts for a single unit in my case.

Thanks heaps,
Samuel

Hey Samuel!

I would definitely disagree with the rumours that you've heard. I'll admit that there are (some) special circumstances in which doing Ext 2 is beneficial for your study of Ext 1 (mainly, just that extra time spent thinking about Maths), however in general I think you can do just as well, and understand just as much, as any student doing Ext 2. MAYBE Ext 1 seems easy to an Ext 2 student, but that's just because they're often very, very good at maths (and thus doing Ext 2; if they were doing only Ext 1, they would still find it just as easy!).

A better question is asking whether Ext 1 is worth it, since it's only worth one unit. I would still say that it does. The content is definitely less than 2U, which makes sense since you have less class time dedicated to it. You'll do better in 2U if you're studying Ext 1 (lots of techniques translate, and you just spend more time doing maths and thinking about the beauty of numbers), and if you find yourself struggling at any point you can drop the subject. My overall recommendation is that, seeing as you did well in prelim, you should continue your study and decide further down the track (and use this forum if you have any questions!)

Let me know if you have any other specific questions; you've raised some really good points that a lot of students worry about, so I'm glad you asked it here!

Jake
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samuels1999

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Re: 3U Maths Question Thread
« Reply #701 on: September 30, 2016, 09:24:57 pm »
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Thanks very much Jake.

I also have another question regarding Permutations and Combinations. I personally found it the hardest maths topics I have ever done in the sense that, 1. at times I didn't really know what the question was actually asking and 2. there was no way to check my method/ answer.
I just wanted some advice on how to study the topic: Tonnes of Practice? What textbook maybe (Cambridge/ Maths in Focus)? or Maybe just past papers?

Thanks
Samuel

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RuiAce

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Re: 3U Maths Question Thread
« Reply #702 on: October 01, 2016, 01:30:10 am »
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Hi Jake,

I am doing Extension 1 mathematics next year, as I did really well in prelim Ext 1. The thing is, I have heard many rumours from students in the year above me that it is really hard to do Extension 1 by itself (without Ext 2). However they say, it's really easy for people doing Extension 2. I just wanted to know what your take on that is (how true is the statement?) and whether extension 1 is really worth doing as it only counts for a single unit in my case.

Thanks heaps,
Samuel
Those rumours are ridiculous. Seconding everything Jake said.
Thanks very much Jake.

I also have another question regarding Permutations and Combinations. I personally found it the hardest maths topics I have ever done in the sense that, 1. at times I didn't really know what the question was actually asking and 2. there was no way to check my method/ answer.
I just wanted some advice on how to study the topic: Tonnes of Practice? What textbook maybe (Cambridge/ Maths in Focus)? or Maybe just past papers?

Thanks
Samuel
You do practice questions for every single topic. Singling out perms and combs doesn't make a difference.

But it is certainly a more dodgier topic. It's very easy to misinterpret the question and head in the wrong direction. You need to use many fundamental counting principles.
- And implies multiply
- Or implies add
- Difference between selections and arrangements
- Difference between ordered and unordered

Whilst it is possible to categorise different combinatorics questions, it's too easy to go into the wrong category. It really takes heaps of practice. Hence, simply do as many questions as possible. In all honesty, I had minimal confidence with that topic until uni, and even now I'm not that confident anyhow.

I've never used Cambridge for perms and combs. Maths in focus makes it smoother because it's all categorised into topics but the questions in maths in focus aren't hard altogether.
« Last Edit: October 01, 2016, 01:42:44 am by RuiAce »

massive

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Re: 3U Maths Question Thread
« Reply #703 on: October 01, 2016, 03:19:17 pm »
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Hey guys, this question looks pretty simple but i'm kind of perplexed because if both A and B have zero velocity doesn't that mean they're both turning points :S and if that's the case how is b>a. I don't get part i because of this lack of understanding of the question. Thanks for and tips!

RuiAce

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3U Maths Question Thread
« Reply #704 on: October 01, 2016, 03:44:27 pm »
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Read the question again. b and a are actually y-coordinates, not x-coordinates

(Or technically I should say they are x-coordinates and not t-coordinates)

They can definitely both be stationary points because SHM is described by a sine curve, which has infintely many stationary points