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Author Topic: 3U Maths Question Thread  (Read 1516569 times)  Share 

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RuiAce

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Re: 3U Maths Question Thread
« Reply #2850 on: October 04, 2017, 10:46:19 pm »
+3
Hey ATARNotes!

With regards to proving binomial identities, instead of starting with the typical (1+x)^n, could we just prove the identity straight up?
I found a binomial question that was in the 1999 Killara trial, and I couldn't prove it from the (1+x)^n expansion.

I managed to prove it from RHS to LHS, though.


If they specify a method, then you must use it to obtain the marks.

This question has been asked before.

winstondarmawan

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Opengangs

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Re: 3U Maths Question Thread
« Reply #2852 on: October 05, 2017, 10:29:02 pm »
+5
3d iii)


Thus, parallel (corresponding angles are equal).
You could have stopped knowing the alternate segment theorem, and use part (ii).

5d (ii) I'll skip the first step, as I assume you know how to do it.





The part that's not showing in my preview is basically the substitution from part i, where n is equal to (k+1). When we substitute the RHS of part i, we can factorise and it should come out nicely.

6b)
(i) P(at least three of its members not complete) = P(3 not complete) + P(4 not complete)



(ii) To score a point, at least half will complete. Thus, we need at least 2 people to complete it, meaning we need 0 or 1 to not pass.



(iii) Again, probability that a two-member team will score is when only zero fail.



(iv)

7b)
Using the arc length-radius-central angle property,


« Last Edit: October 05, 2017, 11:54:29 pm by Opengangs »

K9810

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Re: 3U Maths Question Thread
« Reply #2853 on: October 06, 2017, 02:45:05 pm »
0
Hey,
How can I solve this question?

RuiAce

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Re: 3U Maths Question Thread
« Reply #2854 on: October 06, 2017, 03:05:51 pm »
+4
Hey,
How can I solve this question?





At this point, you can finish it off via just the quadratic formula
« Last Edit: October 06, 2017, 04:58:59 pm by RuiAce »

supR

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Re: 3U Maths Question Thread
« Reply #2855 on: October 07, 2017, 07:46:23 pm »
0
Hey ATAR Notes, this is my first post!!

I attended the MX1 lecture today, where we covered Rates of Change and Induction.
Induction really sat well with me, and after doing some more questions I feel pretty confident on it!

However, Rates of Change has been more of a struggle since leaving the lecture hall.
In particular, I was trying to do some Cambridge questions and I got stuck. I have attached the question, and was hoping someone could help me?  ;D
I can show the equations, but am unsure on parts a) and b).


HSC 2018 - 98.50 ATAR
Please check out my Youtube c: I upload every Tuesday and Friday c: https://www.youtube.com/channel/UCL1c_bBjSE6oNNYgt4CK0DA

RuiAce

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Re: 3U Maths Question Thread
« Reply #2856 on: October 07, 2017, 08:17:57 pm »
+3
Hey ATAR Notes, this is my first post!!

I attended the MX1 lecture today, where we covered Rates of Change and Induction.
Induction really sat well with me, and after doing some more questions I feel pretty confident on it!

However, Rates of Change has been more of a struggle since leaving the lecture hall.
In particular, I was trying to do some Cambridge questions and I got stuck. I have attached the question, and was hoping someone could help me?  ;D
I can show the equations, but am unsure on parts a) and b).

That was it for part a)
________________________________________________________________________



________________________________________________________________________


I leave the last bit as your exercise.

skullcandy

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Re: 3U Maths Question Thread
« Reply #2857 on: October 09, 2017, 07:30:01 pm »
0
Please help solve:


RuiAce

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Re: 3U Maths Question Thread
« Reply #2858 on: October 09, 2017, 09:35:57 pm »
+4
Please help solve:

(Image removed from quote.)


A nice starting point may be \(x_0 = \frac12\). Because they give you no starting point, you pick any valid one. This choice was picked by noting that \( 10^{1/3}\approx 2 \), so \( 10^{-1/3}\approx \frac12 \)

To estimate it to 4 decimal places, you keep applying it until the first four decimal places no longer change. If you choose the value I provided, according to the calculator this happens after five iterations (i.e. the first four decimal points after applying Newton's method 5 times stays the same.)
« Last Edit: October 09, 2017, 09:46:55 pm by RuiAce »

Nick Seb

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Re: 3U Maths Question Thread
« Reply #2859 on: October 10, 2017, 12:44:10 am »
0
Yo, quick question, do we need to know both T-ratios AND the auxiliary angle method for the HSC, or will knowing just one suffice?

Cheers,
Nick

jamonwindeyer

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Re: 3U Maths Question Thread
« Reply #2860 on: October 10, 2017, 12:45:52 am »
+2
Yo, quick question, do we need to know both T-ratios AND the auxiliary angle method for the HSC, or will knowing just one suffice?

Cheers,
Nick

Welcome to the forums mate! Unfortunately you do need to know both - But you can have a favourite you default too. Auxiliary is asked more than t-results though, as a heads up ;D

skullcandy

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Re: 3U Maths Question Thread
« Reply #2861 on: October 10, 2017, 09:11:52 pm »
0


A nice starting point may be \(x_0 = \frac12\). Because they give you no starting point, you pick any valid one. This choice was picked by noting that \( 10^{1/3}\approx 2 \), so \( 10^{-1/3}\approx \frac12 \)

To estimate it to 4 decimal places, you keep applying it until the first four decimal places no longer change. If you choose the value I provided, according to the calculator this happens after five iterations (i.e. the first four decimal points after applying Newton's method 5 times stays the same.)


RuiAce

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Re: 3U Maths Question Thread
« Reply #2862 on: October 10, 2017, 09:13:33 pm »
0
(Image removed from quote.)
So because the first few decimal points don't change anymore, your answer is 0.4642 (because you would need to round up)

winstondarmawan

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« Last Edit: October 10, 2017, 09:24:32 pm by winstondarmawan »

RuiAce

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Re: 3U Maths Question Thread
« Reply #2864 on: October 10, 2017, 09:43:27 pm »
+4
Would appreciate help with the following from 2004 HSC:
https://scontent-syd2-1.xx.fbcdn.net/v/t35.0-12/22429083_1346848178774035_1409548939_o.png?oh=1eb0a1128db626478e1406ed14d3cec1&oe=59DE124F
Part (iv). TIA


It can be hard to keep track of the terms.
________________________________________________________



This is deduced in a similar way to how we found the expression in part i). The idea is that \( (1+x)^{n-1} +\dots + (1+x) + 1 = \frac{(1+x)^n-1}{x} \), and we now need the coefficient of \( x^k \) in this one.


________________________________________________________

Added to the compilation.
« Last Edit: October 10, 2017, 09:46:35 pm by RuiAce »