Author Topic: IGCSE MATHS Doubts  (Read 129693 times)

Offline NidZ- Hero

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Re: IGCSE MATHS Doubts
« Reply #915 on: May 18, 2010, 05:57:41 pm »

Offline Ghost Of Highbury

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Re: IGCSE MATHS Doubts
« Reply #916 on: May 18, 2010, 05:58:42 pm »
can some1 plz explain jun 2007 p4 q 2f and 4 c-e  :)

take 2 sets of c-ordinates (2,1) (3,3)

 (1 0) * (2 3)  = (2  3)
 (-1 1)  (1  3)    (-1 0)

do the same with the other co-ordinate

(2,1) --> (2,-1)
(3,3) --> (3,0)
(5,1) --> (5,-4)

ii) https://studentforums.biz/index.php/topic,5575.msg167872.html#msg167872

   check that..

   if u see carefully, its the matrix which represents..shear of shear factor = -1 and y invariant.

iii) inverse of the transformation matrix which mapped ABC to A3B3C3

   that is inverse of (1 0) = (1  0)
                          (-1 1)   (1  1)

4c) this means that find two values for 'y' for which there are 2 values of x for each of them

       for this u have to use the graph, check the diagram..
put straight lines where u think the line will intersect the graph twice..

(red lines)

ull notice, that wen y = 3...x has 2 values..

also, wen y = -9, x has two values

4e) f(x) + x -1 =0

     as f(x)=y

    y+x-1 = 0

   y = 1-x

   draw the line y = 1-x in the graph

eii)  it cuts the graph at 3 points...meaning it has 3 solutions

« Last Edit: May 18, 2010, 06:11:55 pm by A@di »
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Offline saleemsamer

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Re: IGCSE MATHS Doubts
« Reply #917 on: May 18, 2010, 06:02:53 pm »
take 2 sets of c-ordinates (2,1) (3,3)

 (1 0) * (2 3)  = (2  3)
 (-1 1)  (1  3)    (-1 0)

do the same with the other co-ordinate

(2,1) --> (2,-1)
(3,3) --> (3,0)
(5,1) --> (5,-4)

ii) https://studentforums.biz/index.php/topic,5575.msg167872.html#msg167872

   check that..

   if u see carefully, its the matrix which represents..shear of shear factor = -1 and y invariant.

iii) inverse of the transformation matrix which mapped ABC to A3B3C3

   that is inverse of (1 0) = (1  0)
                          (-1 1)   (1  1)

Thank You but wat abt 4

Offline Vin

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Re: IGCSE MATHS Doubts
« Reply #918 on: May 18, 2010, 06:03:16 pm »


oh sorry
its minus


wats the answer ?? did u type the correct ques =P .. i think i got it ..

Offline Vin

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Re: IGCSE MATHS Doubts
« Reply #919 on: May 18, 2010, 06:04:05 pm »
thanz a Lot a big confusion  :D

which one u talkin abt ?? u didnt get it ??

Offline Ghost Of Highbury

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Re: IGCSE MATHS Doubts
« Reply #920 on: May 18, 2010, 06:07:08 pm »

Thank You but wat abt 4

check again.

@ksitna -
check the question again.
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Offline NidZ- Hero

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Re: IGCSE MATHS Doubts
« Reply #921 on: May 18, 2010, 06:12:40 pm »
which one u talkin abt ?? u didnt get it ??
2006 m/j 2 d its 4 marks

Offline saleemsamer

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Re: IGCSE MATHS Doubts
« Reply #922 on: May 18, 2010, 06:13:11 pm »
check again.

@ksitna -
check the question again.
Thank You  :)

Offline Kojoudeh95

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Re: IGCSE MATHS Doubts
« Reply #923 on: May 18, 2010, 06:16:48 pm »
Can some1 plz tell me a good way of finding the scale factor of a shear and stretch??? And wat should u say wen they tell u describe a transformation: 1) shear description
                      2) stretch description

PLZ and thx :D

Offline Ghost Of Highbury

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Re: IGCSE MATHS Doubts
« Reply #924 on: May 18, 2010, 06:20:26 pm »
Hi guys,

I'm new here... Been reading these posts for a couple days now, but just didn't have any personal questions. UNTIL NOW.
I have a problem with a function graph - I need help with O/N 2001 Paper 4, question 6a.) iii.
How do you use a graph to find an inverse function?

If anyone could explain, I'd REALLY appreciate it - Paper tomorrow!!! Thanks :)

(paper + mark scheme attached)

ok look

first u have to understand wats the relation b/w g(x) and g-1(x)

e.g : say g(x) = x+2

    thus, g(2) = 4

g-1(x) = x-2

now, if u apply 4 in g-1(x) , u will get 2

another e.g - g(4) = 6, apply 6 in g-1(x) and u get 4

same thing here...they've asked g-1(-0.5)

meaning, wat do u have to apply in g(x) to get -0.5 ?? meaning g(x) = -0.5, y = g(x), thus, y = -0.5...draw this line and see where it intersects y = g(x)

from the graph , it intersects at x = -1

this means that if u apply -1 in g(x) u get -0.5

thus if u apply -0.5 in g-1(x) u'll get -1.

:D
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Offline Vin

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Re: IGCSE MATHS Doubts
« Reply #925 on: May 18, 2010, 06:23:20 pm »
2006 m/j 2 d its 4 marks

Area of CBAED = 365 cm2 u got in b)
multiply by 2  .. two sides
= 730 cm2

area of 'yellow' part .. u kno the perimeter so*40 add u get ..

imagine u cut open the yellow part ... it forms a triangle

Offline $H00t!N& $t@r

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Re: IGCSE MATHS Doubts
« Reply #926 on: May 18, 2010, 06:23:46 pm »
@VIN
oh im really sry for disturbing you. sry i made you do all that. i completely understand it now. thx a zillion!!! gdluck with both, french and maths!
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A=X+Y+Z, X is work. Y is play. Z is keep your mouth shut"- Albert Einstein

Offline Ghost Of Highbury

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Re: IGCSE MATHS Doubts
« Reply #927 on: May 18, 2010, 06:35:12 pm »
Also having trouble with probability - O/N 2002 Paper 4 Q4 a. iii.) and b. iv. and v.)
 :'(

Thanks in advance to anyone who can help me out

4aiii) probability that the no. is shaded : 4/10

        prob. that the no. is even : 5/10

   4/10 + 5/10 = 9/10

however, it cant be 2 or 4, because they're shaded and even...prob. of getting 2 or 4 = 2/10

  9/10 - 2/10 = 7/10

biv) possibilities : (1,1) (2,1) (1,2)

(1,1) = 1/10 * 1/10 = 1/100    

(2,1) = 1/100

(1,2) = 1/100

1/100 + 1/100 + 1/100 = 0.03
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Offline Ghost Of Highbury

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Re: IGCSE MATHS Doubts
« Reply #928 on: May 18, 2010, 06:43:55 pm »
thanks so much! i hate that feeling when i realize i was making stupid mistakes the entire time and the question is actually so much easier than i originally thought... <kicks self>

no problem..
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Offline Airhead

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Re: IGCSE MATHS Doubts
« Reply #929 on: May 18, 2010, 06:48:19 pm »
Can anyone help me out with M/J 2008, question 4 part c? It's a little confusing :P