Maths Ext 2 Predictions (1 Viewer)

[Blobrocks]

Yeah what is it?

 

[drani]

Was 10B or D in the end? Because if you do a dot product a + b + c => costheta = magnitude a^2 + a.b + a.c / magnitude a root(a^2 + b^2 + c^2)
- and a and b and c were unit vectors so = root3 on the bottom and a perpendicular to b and c so on the top you get 1

It was D. I attached a pdf I made that shows how people got B and why D was right so hopefully it’s clear

 

[K2Trappy]

It was D. I attached a pdf I made that shows how people got B and why D was right so hopefully it’s clear

damn ppl are actually too cooked at maths, I look at that shi and said I haven't choose C in a while

 

[anonymous1111]

the easiest way to do 10 is to get |a+b+c|^2 = (a+b+c).(a+b+c) = 3 + 2a.c
so a.(a+b+c) = |a||a+b+c|cos(t) --> 1+a.c = sqrt(3+2a.c)cos(t) --> cos(t) = (1+a.c)/sqrt(3+2a.c).
Now if a = c, then cos(t) = 2/sqrt(5) which is biggest value cos(t) can be under this restriction, thus the smallest angle.

Ive seen too many overly complicated methods for this.

Also the e^z one is not oos you can do e^(x+iy) = e^x e^iy= e^x(cis(y)) then conjugate that.

 

[herbimycin]

damn ppl are actually too cooked at maths, I look at that shi and said I haven't choose C in a while

real asf. as soon as a multiple choice question has more than a line of information in the question i'm out

 

[zackbekro123]

It was D. I attached a pdf I made that shows how people got B and why D was right so hopefully it’s clear

makes sense read a perpendicular b and a perpendicular c instead of b perpendicular c

 

[C2H6O]

For question 11 f, sketching the region on the argand plane, would there be 1 open circle at (0, i) or 3 open circles the other 2 being at the intersections of the sector and the dashed circle? bc technically at those points z does not satisfy |z|<3? I put 3 open circles but I've only seen solutions with 1 so far?

 

[herbimycin]

For question 11 f, sketching the region on the argand plane, would there be 1 open circle at (0, i) or 3 open circles the other 2 being at the intersections of the sector and the dashed circle? bc technically at those points z does not satisfy |z|<3? I put 3 open circles but I've only seen solutions with 1 so far?

i doubt that 3 open circles would be needed as its already shown through the dotted circle that that point is not included (i think). But you definitely would not be marked down for it.

 

[K2Trappy]

For question 11 f, sketching the region on the argand plane, would there be 1 open circle at (0, i) or 3 open circles the other 2 being at the intersections of the sector and the dashed circle? bc technically at those points z does not satisfy |z|<3? I put 3 open circles but I've only seen solutions with 1 so far?

I don't think it matters, dotted line signifies that point isn't part of the diagram anyway so putting a circle is unnecessary doubt you'll lose marks

 

[C2H6O]

Thank God cause I really can't afford to loose any more

 

[mystic router]

whats ur school rank at nsb

id rather not dox myself, top 10

 

[mystic router]

do yk me and blobrocks?

yeah, dyk me?

 

[tywebb]

do you really take the media seriously when they hone in on just 1 question in their articles on maths exams? like in https://www.smh.com.au/national/nsw...question-bowen-solved-it-20241021-p5kjwt.html

maybe use https://12ft.io/ to circumvent paywall

it takes it way out of context. it also often exaggerates the difficulty of the last question and ignores the other issues like the one currently dominating the debate about the oosiness of question 8

 

[tywebb]

just for the record, no, i don’t take them seriously at all.

 

[tywebb]

if they want me to take them seriously, i expect an entire issue of the smh dedicated to the non-oosiness of the question to be published tomorrow.

i play hard-ball.

meaning they won’t publish that

so not only will i not take them seriously, but nobody else will either.

 

[Allan Mekisic]

Also what was the point of Q16a. It was not extension 2 maths. It was advanced maths. They dressed it up like it was SHM but it was just m1x m2 =-1. Sure it looked elegant but had nothing to do with SHM or extension 2 maths.

 

[lmkae]

do you really take the media seriously when they hone in on just 1 question in their articles on maths exams? like in https://www.smh.com.au/national/nsw...question-bowen-solved-it-20241021-p5kjwt.html

maybe use https://12ft.io/ to circumvent paywall

it takes it way out of context. it also often exaggerates the difficulty of the last question and ignores the other issues like the one currently dominating the debate about the oosiness of question 8

Wait which aspect of Q8 is out of syllabus? I thought it was a pretty simple manipulation

 

[tywebb]

Wait which aspect of Q8 is out of syllabus? I thought it was a pretty simple manipulation

yeah that’s one school of thought.

another would be that algebraic manipulations with complex exponents are not in the syllabus

not helpful is the propensity for much syllabus content to be expressed in excessively useless and meaningless platitudes

one may argue that such vagary allows for more creativity in exams, but others may argue that it opens it up for accusations for oosiness

 

[femboys4life]

do you really take the media seriously when they hone in on just 1 question in their articles on maths exams? like in https://www.smh.com.au/national/nsw...question-bowen-solved-it-20241021-p5kjwt.html

maybe use https://12ft.io/ to circumvent paywall

it takes it way out of context. it also often exaggerates the difficulty of the last question and ignores the other issues like the one currently dominating the debate about the oosiness of question 8

media is for the masses, u rlly reckon general public is gonna be interested in a conversation about "mm yes the manipulation of the complex exponents falls outside the syllabus due to the general invalidation of exponential rules with non-integer values for the complex number system"

anyone who knows their stuff doesnt give 2 cents for what the mainstream media has to say, especially for ext 2 maths

 

[drani]

yeah that’s one school of thought.

another would be that algebraic manipulations with complex exponents are not in the syllabus

not helpful is the propensity for much syllabus content to be expressed in excessively useless and meaningless platitudes

one may argue that such vagary allows for more creativity in exams, but others may argue that it opens it up for accusations for oosiness

I don't know about it being OOS. We know how to manipulate complex numbers written in Euler's form which was sufficient to solve question 8. I mean if it really was OOS, they probably wouldn't make the answer impossible to come up with. So with that in mind I immediately jumped to A because it seemed correct intuitively & looked the most simple. We know that z bar would be x-iy, and if we have e^x-iy, we can just treat that as e^x multiplied by e^-iy which can then be expressed in mod arg form, and e^x is obviously scalar and with a bit of manipulation you'd reach the answer of A. It probably wasn't everyones first thought to eliminate C and D based off it "not looking right" though.