MedVision ad

Mathematics Extension 2 Predictions (3 Viewers)

tgone

Well-Known Member
Joined
Mar 2, 2022
Messages
182
Gender
Male
HSC
2022
So kind for a student who just came here for two years, questions are abstract and see you E4.......
yeah it was like a really abstract test that’s a good way of putting it but for the most part just going through with calculations got to the required result so I think it’s ok- predicting a very low E4 cutoff this year though so don’t be too disappointed
 

sga2

New Member
Joined
Oct 20, 2022
Messages
3
Gender
Male
HSC
2022
did anyone know how to do the final part of q.16?
 

tgone

Well-Known Member
Joined
Mar 2, 2022
Messages
182
Gender
Male
HSC
2022
Bruh how, q16 b took too long I gave up on it
you can write “vector” CB = e^(ipi/3)CA since it’s equilateral
i’m just going to use zA=a, zB=b, zC=c
i.e.
b-c=(a-c) e^(ipi/3)
so b=c(1-e^(ipi/3))+ae^(ipi/3)

we know that:
b=xb+5i
c=xc-5i

subbing c and a into above the expression for b, you get an expression for b in terms of xc, and you can solve for xc by using Im(b)=5
 

tgone

Well-Known Member
Joined
Mar 2, 2022
Messages
182
Gender
Male
HSC
2022
@tgone wtf they actually asked the same question as this in this year’s HSC (with minor variations)….
yeah literally i looked at it in reading time and did a double take … thought what the heck did he know about it… so glad i did it thank you so much 😆
 

tgone

Well-Known Member
Joined
Mar 2, 2022
Messages
182
Gender
Male
HSC
2022
@tgone wtf they actually asked the same question as this in this year’s HSC (with minor variations)….
although to be fair when you sent I just skimmed over it and thought yeah I think I can do this after a bit of thinking so it just made it quicker in the test rather than letting me know how to do it
 

yanujw

Well-Known Member
Joined
May 23, 2020
Messages
339
Gender
Male
HSC
2022
yeah literally i looked at it in reading time and did a double take … thought what the heck did he know about it… so glad i did it thank you so much 😆
Same lol it took me by surprise when I first saw it, thinking about how it looked really similar
 

synthesisFR

afterhscivemostlybeentrollingdonttakeitsrsly
Joined
Oct 28, 2022
Messages
3,312
Location
Getting deported
Gender
Female
HSC
2028
To try find the substitutions the trick is often to try match up the powers. For example, if I was like prove that a^4+b^4+c^4>abc(a+b+c), you see the 4th power so instantly you're thinking along the lines of Am-Gm for four. Then, you see three terms on the LHS and you notice that on the RHS you've got a^2bc, so a is twice the power. Therefore a good guess would be Am-Gm for a^4+a^4+b^4+c^4≥4a^2bc. And you'll find that this works out if you to it for b and c and add them together. Like fr it's tricky but there are some hints in the question itself and it helps you narrow it down to like a couple guesses. Idk if this helps
Question
R u allowed to just use am hm of threes or fours without proving it first
 

Users Who Are Viewing This Thread (Users: 0, Guests: 3)

Top