Login

Welcome, Guest. Please login or register.

March 29, 2024, 10:48:37 am

Author Topic: 4U Maths Question Thread  (Read 659923 times)  Share 

0 Members and 8 Guests are viewing this topic.

jamonwindeyer

  • Honorary Moderator
  • Great Wonder of ATAR Notes
  • *******
  • Posts: 10150
  • The lurker from the north.
  • Respect: +3108
Re: 4U Maths Question Thread
« Reply #840 on: February 20, 2017, 12:52:56 pm »
0
Can i just ask- how did you get to this (iz=(3+2i)z-3-2i) step? I don't understand the continuation from the previous step to this one.

Heres the step in between! It's just expansion and then re-factorisation (or partial expansion, if you will) ;D


michaelalt

  • Trailblazer
  • *
  • Posts: 41
  • Respect: 0
Re: 4U Maths Question Thread
« Reply #841 on: February 20, 2017, 12:54:34 pm »
0
Heres the step in between! It's just expansion and then re-factorisation (or partial expansion, if you will) ;D



Ahhhh! I get it! Thank you Jamon!!

michaelalt

  • Trailblazer
  • *
  • Posts: 41
  • Respect: 0
Re: 4U Maths Question Thread
« Reply #842 on: February 20, 2017, 12:59:38 pm »
0
Hey hey! Here is the working for this question! ;D



You can then manipulate that answer any way that suits you - I hope that helps! ;D I'll get to your next question in a little bit ;D



When you go on to this ((3+i)z=3+2i) step, where did the iz on the left hand side go?

kiwiberry

  • HSC LECTURER
  • Forum Obsessive
  • ***
  • Posts: 315
  • Respect: +97
Re: 4U Maths Question Thread
« Reply #843 on: February 20, 2017, 01:20:00 pm »
0
When you go on to this ((3+i)z=3+2i) step, where did the iz on the left hand side go?
HSC 2017: English Adv (93) | Maths Ext 1 (99) | Maths Ext 2 (97) | Chemistry (95) | Physics (95)
ATAR: 99.85

kiwiberry

  • HSC LECTURER
  • Forum Obsessive
  • ***
  • Posts: 315
  • Respect: +97
Re: 4U Maths Question Thread
« Reply #844 on: February 20, 2017, 01:33:44 pm »
+1
This makes sense! However, I tried doing part (b.) and it didn't work out as well as I thought it would...
From your second line:

Solve simultaneously from here :)
HSC 2017: English Adv (93) | Maths Ext 1 (99) | Maths Ext 2 (97) | Chemistry (95) | Physics (95)
ATAR: 99.85

michaelalt

  • Trailblazer
  • *
  • Posts: 41
  • Respect: 0
Re: 4U Maths Question Thread
« Reply #845 on: February 20, 2017, 07:42:57 pm »
+2
From your second line:

Solve simultaneously from here :)

youre the best. it makes so much sense and seems so simple when you do it, thanks heaps!

smile123

  • Trailblazer
  • *
  • Posts: 25
  • Respect: 0
  • School: cerdon college
  • School Grad Year: 2016
Re: 4U Maths Question Thread
« Reply #846 on: February 21, 2017, 12:48:18 pm »
0
please help

RuiAce

  • ATAR Notes Lecturer
  • Honorary Moderator
  • Great Wonder of ATAR Notes
  • *******
  • Posts: 8814
  • "All models are wrong, but some are useful."
  • Respect: +2575
Re: 4U Maths Question Thread
« Reply #847 on: February 21, 2017, 12:57:59 pm »
0

smile123

  • Trailblazer
  • *
  • Posts: 25
  • Respect: 0
  • School: cerdon college
  • School Grad Year: 2016
Re: 4U Maths Question Thread
« Reply #848 on: February 21, 2017, 01:04:43 pm »
0
thanks  :)

michaelalt

  • Trailblazer
  • *
  • Posts: 41
  • Respect: 0
Re: 4U Maths Question Thread
« Reply #849 on: February 21, 2017, 01:19:59 pm »
0
How would you approach this question? I tried expanding it out but it got really messy and I just got confused :(

jakesilove

  • HSC Lecturer
  • Honorary Moderator
  • Part of the furniture
  • *******
  • Posts: 1941
  • "Synergising your ATAR potential"
  • Respect: +196
Re: 4U Maths Question Thread
« Reply #850 on: February 21, 2017, 01:30:10 pm »
0
How would you approach this question? I tried expanding it out but it got really messy and I just got confused :(

Hey!

Start by writing everything out in cis form.




Then, use DeMoivre's




Finally, use cis rules to get the answer. Remember that when we divide one complex number in mod-arg form by another, we divide their modulus and subtract their argument. I'll leave that bit to you :)
« Last Edit: February 21, 2017, 01:32:23 pm by jakesilove »
ATAR: 99.80

Mathematics Extension 2: 93
Physics: 93
Chemistry: 93
Modern History: 94
English Advanced: 95
Mathematics: 96
Mathematics Extension 1: 98

Studying a combined Advanced Science/Law degree at UNSW

michaelalt

  • Trailblazer
  • *
  • Posts: 41
  • Respect: 0
Re: 4U Maths Question Thread
« Reply #851 on: February 21, 2017, 01:46:29 pm »
0
Hey!

Start by writing everything out in cis form.




Then, use DeMoivre's




Finally, use cis rules to get the answer. Remember that when we divide one complex number in mod-arg form by another, we divide their modulus and subtract their argument. I'll leave that bit to you :)

Hey Jake- thank you! That makes sense, however, I don't really understand what to do after this...

jakesilove

  • HSC Lecturer
  • Honorary Moderator
  • Part of the furniture
  • *******
  • Posts: 1941
  • "Synergising your ATAR potential"
  • Respect: +196
Re: 4U Maths Question Thread
« Reply #852 on: February 21, 2017, 01:56:24 pm »
0
Hey Jake- thank you! That makes sense, however, I don't really understand what to do after this...

Just what I wrote above; when we divide two complex numbers in cis notation, we divide their modulus and subtract their argument. So,



You can use this to get the final answer
ATAR: 99.80

Mathematics Extension 2: 93
Physics: 93
Chemistry: 93
Modern History: 94
English Advanced: 95
Mathematics: 96
Mathematics Extension 1: 98

Studying a combined Advanced Science/Law degree at UNSW

smile123

  • Trailblazer
  • *
  • Posts: 25
  • Respect: 0
  • School: cerdon college
  • School Grad Year: 2016
Re: 4U Maths Question Thread
« Reply #853 on: February 21, 2017, 07:42:20 pm »
0
please help

beau77bro

  • Forum Obsessive
  • ***
  • Posts: 342
  • Respect: +6
Re: 4U Maths Question Thread
« Reply #854 on: February 21, 2017, 11:00:18 pm »
0
Heyyyy I keep forgetting how to do this question someone please help hahaha ty