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Updates / GCSE Maths Revision [Apr. 3rd, 2007|02:46 pm]
Unofficial Murderous Maths Forum on LJ

ummf_on_lj

[yayworthy]
[Mood |curiouscurious]

This place is suffering from a little bit of deadness, which I now hope to rectify.

Firstly, the following changes have occured to the links list found on the userinfo page:
1) the maths fanlisting has moved to here.
2) there is now a pi fanlisting [yay!] which can be viewed here.

Secondly, and I've probably asked over on UMMF before but can't remember where, it's exam time again, and as usual, I have no idea how to revise for maths. Tips?

On a very related subject, I've scoured the internet for past papers, and all OCR's website could offer was one specimen paper. If anyone can find some terminal papers for the OCR Mathematics C specification higher tier, much pi would be sent in your direction. Thanking you. Also, would it be a bad move to find past papers from different specifications/boards? [In this I am assuming most GCSE maths exams cover similar topics].

p2tp! :)
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Comments:
From: (Anonymous)
2007-04-15 01:48 pm (UTC)
Hi, I'm not sure how to use this site really, but I was after some maths help?!
Have looked everywhere on the net and can't seem to find a website...

Would you be able to show me the working out in how to solve this problem? (Equality of Complex numbers)

2x + 3yi = -x -6i

Please & Thankyou !!!!
(Reply) (Thread)
[User Picture]From: yayworthy
2007-04-19 04:11 pm (UTC)
Hi.

Complex numbers is not in the realm of my current knowledge, as you may know if you are aware of the general syllabus content of maths GCSEs, which as explained in my post I'm currently studying for.

I have however posted your question on UMMF, the forum from which this LJ spin off was created, where there are many people much smarter and more knowledgable than me. If you don't have a UMMF account, you won't be able to see responses as they occur, but I'll keep you posted. :)

I apologise for the lateness of my response, I switched off comment emails a while ago, as they were sending repeats emails for the same comment, thus clogging my inbox, and thus I wasn't aware of it until now.

Thanks for visiting ummf_on_lj, by the way. If you do become an LJ user, please feel free to join the community!
(Reply) (Parent) (Thread)
[User Picture]From: yayworthy
2007-04-19 07:57 pm (UTC)
The following is from the UMMF user snowyowl and is so far not been shown to be incorrect:

2x + 3yi = -x -6i
3x+3yi=-6i
3(x+yi)=-6i
x+yi=-2i
x+(y+2)i=0
x=-(y+2)i
So I think that it is true when x=-(y+2)i


Hopefully this helps. :)
(Reply) (Parent) (Thread)
[User Picture]From: yayworthy
2007-04-20 06:16 pm (UTC)
More from snowyowl:

As y=-2+xi
1) If x and y is real,
As y is real, Im(y)=0
therefore xi=0
But x is real, therefore x=0, then we get y=-2
2) If x is complex (not real), y is real
As same as 1)
xi=0
Let x=a+bi, a,b is real.
xi=ai+bi(i)=ai-b
But xi is real,
therefore Im(xi)=Im(ai-b)=a=0
Therefore a=0, b is real
From a=0, b is real
x=bi, b is any real number, which makes y=-b-2
3) If x is real, y is complex (not real)
From y=-2+xi
If x=0, from (1) y=-2
If x is not 0, then, Im(y)=Im(-2+xi)=x which is not 0
Re(y)=Re(-2+xi)=-2 which is not 0
therefore y is complex
x is any real, y=-2+xi
4) If x and y is complex (not real)
Let x=a+bi
y=c+di when, a,b,c,d are real
From y=-2+xi
c+di=-2+(a+bi)i
c+di=-2+ai-b
c+di=-(b-2)+ai
therefore c=-b-2, d=a
So y=c+di=-(b+2)+ai

So the answers are when
1) x=0, y=-2
2) x=ki, y=-k-2 when k is any real number
3) x=k, y=-2+ki when k is any real number
4) x=a+bi, y=-(b+2)+ai when a,b are any real numbers

But from 4)
If a=b=0
x=0, y=-2 which is the answer from (1)
If a=0
x=bi, y=-(b+2)=-b-2 which is the answer from (2)
If b=0
x=a, y=-2+ai which is the answer from (3)

Therefore the answers of the equation 2x+3yi=-x-6i are when x=a+bi, y=-(b+2)+ai; a,b are any real numbers.


Hope this makes sense!
(Reply) (Parent) (Thread)
From: (Anonymous)
2007-06-23 12:22 pm (UTC)

Thankyou Heaps! :)

Thank you so much for the help!!! :)
GREATLY appreciated...no probs about the late reply. :)
(Reply) (Parent) (Thread)
[User Picture]From: yayworthy
2007-06-23 12:28 pm (UTC)

Re: Thankyou Heaps! :)

No problem! =]
(Reply) (Parent) (Thread)