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# IGCSE/ GCSE maths HELP !!! Watch

1. Hi, Help needed. Need to clarify some things :
What is the difference between the " find the coordinates of midpoint of line and finding the gradient.
What is the difference between m=y/x or is it m=Y2-Y1/X2-X1
IS the finding of the co-ordinates ( 2,1 )( 4,5) = 5-4/2 + ( 1-2)/2 ???

How can we plot a graph straight line like y=2x+1 or if they draw a graph and ask to name it ? how could that be done ?

Any tips for triangular sequences and any other hard sequences ?

is (8x+22)2 = factorising (8x+22)(8x+22)
and (2x-9)(2x-9) means = (4x-18 ) ??????

Another question : From PP 0580/21/ oct 2001

Orange party got 11424 votes which was seven eights of Blue party.
Some people voted for other parties.
Calculate how many people voted for Blue party :

11424 x 8/7 = 13056 ANS IN MARKSCHEME.
however why is 8/7 not 7/8s and they wrote 40/35 in it, can someone help me with it ?
How can I be better on those questions ?

difference between fg(x) and fg(-6) ??? composite function.

When doing Matrices, really Im just stuck on those,
those fractions are as one matrix .

x = ( k 2 ) and X2 = 5( 1 0 ) find K.
( 2 -k ) ( 0 1 )

or like this ( 2 0 ) ( m ) = ( 10 )
( 0 -3 ) (n ) ( 1 )

and are those similar questions in Past paper 21 may 2012 0580 CIE

( 1 0 ) has no inverse
( 0 2x-7 )

( 1 0 ) is identity matrix
( 0 x2-8 )

Identity matrix ? What is it ? Should I ignore it when I deal with those questions.

( 1 0 ) represents stretch with factor 3 and x axis invariant.
( 0 x-2 )

How to be good at those answers ???? Any tips ? because I really am bad on those questions !!!

Thanks
2. (Original post by justwork)
Hi, Help needed. Need to clarify some things :
What is the difference between the " find the coordinates of midpoint of line and finding the gradient.
What is the difference between m=y/x or is it m=Y2-Y1/X2-X1
IS the finding of the co-ordinates ( 2,1 )( 4,5) = 5-4/2 + ( 1-2)/2 ???

Thanks
the midpoint is just the middle of the line. The gradient is the angle of the slope of the line . y=mx + c, m is the gradient and c is the y intercept, which is where the line crosses the y axis.
3. cool got it, but what about the other questions ?
4. (Original post by justwork)
cool got it, but what about the other questions ?
Are you working without any teaching support or books? You've posted questions that are across the range of the syllabus, which suggests you should get your teacher to clarify some of the things you don't understand.

To answer one of your questions, the identity matrix is a square matrix that has the number 1 as each entry on its main diagonal, and 0 in every other element of the matrix.
5. (Original post by justwork)
Identity matrix ? What is it ? Should I ignore it when I deal with those questions.
Thanks
6. Joostan, thanks for visiting. My problem is not with identity matrix but with matrices and algebra ! How can I solve those questions, they carry hefty marks and would love to be excellent at them. Are the matrix with stretch is the same as the one with ( k and -k ?)
thanks alot
7. (Original post by justwork)
Joostan, thanks for visiting. My problem is not with identity matrix but with matrices and algebra ! How can I solve those questions, they carry hefty marks and would love to be excellent at them. Are the matrix with stretch is the same as the one with ( k and -k ?)
thanks alot
One of your questions in the the original post was precisely about what the identity matrix was!!

If you use the definition that Joostan and I gave you, you can solve the question about the matrix containing very easily
8. (Original post by justwork)
Joostan, thanks for visiting. My problem is not with identity matrix but with matrices and algebra ! How can I solve those questions, they carry hefty marks and would love to be excellent at them. Are the matrix with stretch is the same as the one with ( k and -k ?)
thanks alot
Stretch scale factor k, parallel to y-axis (or x-axis invariant)

Stretch scale factor k, parallel to x-axis (or y-axis invariant)

If negative k: http://www.bbc.co.uk/schools/gcsebit...nshirev1.shtml
9. It would really be helpful if someone could show the steps, hard to work on clues when your not confident in this topic.

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10. (Original post by justwork)
It would really be helpful if someone could show the steps, hard to work on clues when your not confident in this topic.

Posted from TSR Mobile
I'm not really sure what your question is
11. (Original post by justwork)
What is the difference between m=y/x or is it m=Y2-Y1/X2-X1

How can we plot a graph straight line like y=2x+1 or if they draw a graph and ask to name it ? how could that be done ?

and (2x-9)(2x-9) means = (4x-18 ) ??????

Orange party got 11424 votes which was seven eights of Blue party.
Some people voted for other parties.
Calculate how many people voted for Blue party :

11424 x 8/7 = 13056 ANS IN MARKSCHEME.
however why is 8/7 not 7/8s and they wrote 40/35 in it, can someone help me with it ?
How can I be better on those questions ?
Not really sure what you mean by the bit in bold but if you mean where it asks for the 'difference in Y / difference in X' when finding a gradient, it basically means y1 - y2 / x1 - x2.

Next bit, I am really not sure what you mean, but mx + c = y. C is where the line intersects the Y axis, the gradient is 2. So plot at 1, one to the right and up two would be the next point.

(2x-9)(2x-9), lets expand this out
2x x 2x = 4x^2
2x x -9 = -18x
-9 x 2x = -18x
-9 x -9 = 81
= 4x^2 - 36x + 81
I don't really know what your asking here, and I am certainly not advanced with algrebra, but I dont think those are the same.

The way I would approach that is divide 11424 by 7, and multiply by 8 to get blues vote = 13056. Not sure about what it says in the mark scheme, sorry.

I'm not sure if I answered any of your questions here because I was kind of confused, and I am not advanced at Maths, sorry if I have done anything wrong but I am sure someone here will correct me if I am wrong.

x
12. (Original post by Tinkletea)
...
These are both correct.
13. (Original post by Tinkletea)
The way I would approach that is divide 11424 by 7, and multiply by 8 to get blues vote = 13056. Not sure about what it says in the mark scheme, sorry.

x
yes you are correct, but can you tell me why you did that ? I mean is there a formula where you do that or something similar. Since its correct, I just dont want to make future same type question mistakes !
14. The question is:

Orange party got 11424 votes which was seven eights of Blue party.
Some people voted for other parties.
Calculate how many people voted for Blue party :

It says that 11424 (orange part votes) was seven eights of Blue Party, so 7/8 people voted orange, 8/8 voted blue party. So to work out 8/8, you need to find out what 1/8 is. Since 11424 is 7/8th, you just need to divide the votes by 7 to get 1/8. 11424 / 7 = 1632.

So now you know blue party got 8/8, just multiply 1632 by 8 = 13056.

They always word these sort of things weirdly to confuse people I think.
15. (Original post by Tinkletea)
The question is:

Orange party got 11424 votes which was seven eights of Blue party.
Some people voted for other parties.
Calculate how many people voted for Blue party :

It says that 11424 (orange part votes) was seven eights of Blue Party, so 7/8 people voted orange, 8/8 voted blue party. So to work out 8/8, you need to find out what 1/8 is. Since 11424 is 7/8th, you just need to divide the votes by 7 to get 1/8. 11424 / 7 = 1632.

So now you know blue party got 8/8, just multiply 1632 by 8 = 13056.

They always word these sort of things weirdly to confuse people I think.
Yeah thanks, it got me really weird and I even started to doubt my confidence in maths. Hate those type of questions. But really thanks, youve cleared some things that I had in maths. Thnks !
16. (Original post by justwork)
IS the finding of the co-ordinates ( 2,1 )( 4,5) = 5-4/2 + ( 1-2)/2 ???

I may of misunderstood but do you mean finding the midpoint? the formula for finding the midpoint is (x1 + x2 /2), (y1 + y2 /2.)

=
2+4 / 2 (X)
1+5 / 2 (Y)

= 6/2
= 6/2

= (3, 3)

(I think!)
x
17. (Original post by Tinkletea)
I may of misunderstood but do you mean finding the midpoint? the formula for finding the midpoint is (x1 + x2 /2), (y1 + y2 /2.)

=
2+4 / 2 (X)
1+5 / 2 (Y)

= 6/2
= 6/2

= (3, 3)

(I think!)
x
This is also correct, though perhaps you should read this . . .

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