Maths Ext 2 Predictions (2 Viewers)

[tywebb]

why does everyone need to write solutions smh

they don't

but people want to know how they went as soon as they finish the exam.

so some try to get solutions out within a few hours so people don't have to wait for nesa solution

it is also good, especially in extension 2 to get multiple solutions from various sources to see all the alternative methods

whist for some questions the solutions may be similar or even the same, there will be several where the solutions will be different

 

[tywebb]

13aii said or otherwise

here otherwise method using cross product


good?

 

[tywebb]

i made a slightly easier one


good?

 

[tywebb]

mg is up: https://educationstandards.nsw.edu....-ccd3eec6-76ac-464f-b0d2-ecf60de040b0-pcJJGdt

 

[tywebb]

here cognito solutions: https://www.cognitotuition.com/blog...nsion-2-exam-paper-exemplar-answers-solutions

pdf version attached. they somewat more detailed than nesa's but don't do reasoning for mc

 

[tywebb]

now i bet you think this generalisation of triangle inequality has nothing whatsoever to do with this exam right?


however .............

15aiii said or otherwise and so here is the "or otherwise" method using generalised triangle inequality!

 

[tywebb]

and here is the list of all the or otherwises in this years maths exams

advanced - once in Q30

ext. 1 - once in Q13bii

ext. 2 - 4 times in Q11eii, Q12cii, Q13aii and Q15aiii

 

[tywebb]

here is or otherwise method for 12cii

 

[tywebb]

so that just leaves for ext. 2 the or otherwise method for the 11eii

an obvious way would be binomial expansion method

u dunno the marking criteria during exam, but u do know it 2 mark

they say "obtains correct number in modulus-argument form, or equivalent merit" for 1 mark

not clear here if the binomial expansion would constitute equivalent merit, but that may be made clearer in next years nesa presentation which occurs on or about the last saturday of february

if one proceeds with this we get



but more controvesially some calculators can do the complex numbers so what if one proceeds with this:



do that get the 2 mark? nesa allow calculator, so should they really penalise for using it to get answer?

one may argue it don't show any understanding other than how to press buttons on calculator so don't deserve 2 mark.

on the other hand it does show ability to use whatever technology is available to get answer and use of technology is in syllabus, and so should get the 2 mark.

 

[tywebb]

it also a question of equity. rich kids with all the wiz-bang expensive technology getting answer in a millisecond thereby giving time-advantage to the rich kids, and poorer kids with cheaper calculator that don't do complex number have to do it longer way, losing valuable time in exam.

 

[tywebb]

there is a bit of controversy about 13b now.

here solution:



controversy stems from comments in textbooks the cambridge and steve howard books say something to the effect that



so u notice in above solution the derivation not given.

there are several solutions on the net now, some with derivation, some without

in 2021 there is a question like this and even nesa's solution to that did not give derivation

furthermore syllabus say "use relevant formulae and graphs to solve problems involving simple harmonic motion"

it don't say derive and use, it just say use

so if we go with the cambridge/steve howard narrative it lose mark

but if we follow what syllabus say it don't lose mark