My thoughts on the 2015 Extension 2 paper. (1 Viewer)

Carrotsticks

Retired
Joined
Jun 29, 2009
Messages
9,587
Gender
Undisclosed
HSC
N/A
Multiple Choice:

What is Q3 doing there?

Q10 was a bit too easy for MX2 Q10 I think. A 2 unit student could have worked that one out.

Overall, MC much easier than other years.

Question 11:

(b) (iii) could have had cleaner results. I see no reason why the argument of w had to be pi/7 as opposed to say pi/4 or pi/3 etc. This may have worried students unnecessarily (with them thinking they got the wrong answer).

Why is (f) here? This is a fairly classic 3U integration question. The 3 marks could have been put to better use ie: trig sub, t formula, harder reverse chain rule, f(a-x) etc

Question 12:

I like the idea of (a) (iii), where I'm guessing the intention was for students to make the connection between the vector form and the complex number form.

Question 13:

I think (b) could have been left as a standalone question without any guidance like in the 2012 paper.

Have no idea what (c) is doing here, also given the fact that it is worth SIX marks! Sure, the topic Harder Ext 1 technically can be any Ext 1 topic. But the difficulty of this question hardly warrants it being placed in an Ext 2 paper. The six marks could have been put to better use ie: circle geometry and/or strong induction.

Question 14:

Physics students were clearly conflicted in this question as mu was treated as a variable, when it is usually studied as a constant. Otherwise a nice question.

Question 15:

(a) was a cute question that proved a neat result.

(b) was a good question.

Question 16:

(a) (ii) I'm not sure what markers would be looking for in this question. Mechanically, it is identical to the previous part. Did they want students to copy down their answer from part (i) but use the letters n and q instead of numbers? Also, given that it is question 16, I think (i) and (ii) could have been merged into one question.

(b) is a nice introduction to Tchebyshev polynomials, and how it can be used to prove various identities. Good question. However, expecting students to recall the closed form for the binomial series in part (iii) is being a bit over ambitious, I think.
 

Ekman

Well-Known Member
Joined
Oct 23, 2014
Messages
1,618
Gender
Male
HSC
2015
What are your predictions for the raw cut off marks for a E3, E4 and a state rank?
 

leehuan

Well-Known Member
Joined
May 31, 2014
Messages
5,805
Gender
Male
HSC
2015
I agree with what was Q3 doing there. Free mark.
2U have all the skills they need work out Q10 but the ^n would make them freak out too easily and I reckon it would be a 3U question.
__
29pi/42 almost made me worried so yep.
I actually used t-formula on 11(f) for part (i). But again, you're right, it is a 3u concept because d(theta)=2dt/(1+t^2) was not required. Part (ii) though, 3u would've been forced to say "let u=sin(theta/2)"
__
__
c) was definitely ambiguously placed. I rejoiced over free marks but I felt like I was back in 3u again
__
It's refreshing having F being "related" to N in my opinion. Makes the algebra a bit different. Reckon other physics students were that disturbed by it?
__
I really liked b). Integrating up to 1/n is something I'm sure students would've missed out
__
I do agree heavily. Q16(a)(ii) was the biggest dud I had seen in my whole history of MX2. I basically repeated my process for both questions and was thinking "uh, ok.. carrying on". I even came out having a slight fear that I had made a mistake over it.
Ah so that's what (b) related to this year, eh.
 

InteGrand

Well-Known Member
Joined
Dec 11, 2014
Messages
6,111
Gender
Male
HSC
N/A
I don't think students needed to simplify the binomial sum for the last question part (iii).
 

JAMLO

Member
Joined
Aug 30, 2014
Messages
47
Gender
Male
HSC
2015
For q12 aiii was it wrong if you didn't move the vector to the origin
 

Carrotsticks

Retired
Joined
Jun 29, 2009
Messages
9,587
Gender
Undisclosed
HSC
N/A
For q12 aiii was it wrong if you didn't move the vector to the origin
Doubt they would dock you for that. A vector can be freely moved around. If they asked for position vectors representing various complex numbers (which they didn't) then sure they can dock you.
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top