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Author Topic: [CIE] All Pure Mathematics (P1, P2 and P3) doubts here !  (Read 80254 times)

Offline Dibss

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #90 on: January 05, 2011, 08:20:01 pm »
Quote from: mimiswift on January 05, 2011, 08:06:35 pm
i cant get the correct answer.....................

Like I asked, which part?
-show that the coordinates of one stationary point are (4, kc-80k )
-find, in a similar form the coordinates of the second stationary point.
-show that c=26.
-find the exact value of k.?

Or do you simply want the solution to the whole question without trying for yourself if you can get the other parts by following through after your particular doubt has been cleared? :|
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Offline Tohru Kyo Sohma

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #91 on: January 06, 2011, 01:26:23 pm »
Quote from: Dibss (Whisper) on January 05, 2011, 08:20:01 pm
Like I asked, which part?
-show that the coordinates of one stationary point are (4, kc-80k )
-find, in a similar form the coordinates of the second stationary point.
-show that c=26.
-find the exact value of k.?

Or do you simply want the solution to the whole question without trying for yourself if you can get the other parts by following through after your particular doubt has been cleared? :|
ok......i got it.......thanks alot whisper!  :D
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Offline Tohru Kyo Sohma

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #92 on: January 06, 2011, 01:44:14 pm »
a.A curve has equation; y=96x^2 -x^3, x>0
use differentiation to show that the coordinates of the stationary point are (64, 131072). show further that the stationary point is a maximum point.
b. when a particular makes of a car is driven at a speed of v km/h, where 50<=v<=100, the distance travelled, per litre of fuel, by the car is modeled by;
96v^2 -v^3 +200000/25000 kilometers. for the speed in the range 50km/h to 100 km/h , find the maximum possible speed of kilometers per litre that the car can achieve?

plss hlp me!!!
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elemis

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #93 on: January 06, 2011, 01:46:36 pm »
Doing it.
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elemis

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #94 on: January 06, 2011, 01:54:12 pm »
192x -3x2 = 0

x = 0 or 64

Inputting 64 into original equation gives a y coordinate of : 131,072

Differentiating a second time : 192 - 6x

Inputting 64 in to this equation gives a value of : -192. This is less than zero indicating it is a maximum point.

b) I cant answer this part because I'm unsure of the form of the equation you given. Can you show me the question paper this is from ?
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Offline Arthur Bon Zavi

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #95 on: January 06, 2011, 01:57:09 pm »
What is the answer of (b) ?
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Offline Tohru Kyo Sohma

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #96 on: January 07, 2011, 10:10:58 am »
Quote from: Ari Ben Canaan on January 06, 2011, 01:54:12 pm
192x -3x2 = 0



b) I cant answer this part because I'm unsure of the form of the equation you given. Can you show me the question paper this is from ?
its not from pastpapers.......its from a book....i dont know which book because our teacher only printed the qns and gave it to us to do.
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Offline Tohru Kyo Sohma

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #97 on: January 07, 2011, 10:12:15 am »
Quote from: Fidato on January 06, 2011, 01:57:09 pm
What is the answer of (b) ?
the answer for b is 13.......i dont know how to get to this answer.
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Offline astarmathsandphysics

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #98 on: January 07, 2011, 04:00:00 pm »
distance =(96v^2 -v^3 +200000)/25000
differntiatate wrt v to get (192v-3v^2 )/25000
To find the max put this equal to zero so (192v-3v^2 )/25000= 0 so 192v-3v^2 =0 so 3v(64-v)=0 so v=64
To prove a max differentiate again to get (192-6v )/25000 =(192-6*64 )/25000<0 hence max distance
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Offline Chingoo

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #99 on: January 15, 2011, 08:52:14 am »
M/J 2010 - P32 - Q6

=_= I need help in every bit of it.
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Offline ashish

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #100 on: January 19, 2011, 04:33:49 pm »
Quote from: Chingoo on January 15, 2011, 08:52:14 am
M/J 2010 - P32 - Q6

=_= I need help in every bit of it.

you are talking about cie right?

xlny=2x+1
lny=2+1/x

diff w.r.t x
1/ydy/dx=0-1/x2
dy/dx = -y/x2

tht part 1
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Offline ashish

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #101 on: January 20, 2011, 02:26:23 am »
Quote from: Chingoo on January 15, 2011, 08:52:14 am
M/J 2010 - P32 - Q6

=_= I need help in every bit of it.

xlny-2x=1
x=1/(lny-2)

when y=1
x=-0.5
dy/dx=-4

y=mx+c
1=2+c(substituting all the values)
c=-1

y=-0.5x-1 (*2 throughout)
2y=-x-2
x+2y+2=0
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Offline melony

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #102 on: January 26, 2011, 06:05:25 pm »
wow its been long since i've been here! :P
I REALLY NEED A MATHEMATICIAN! ;D
Please could someone guide me through a step by step solving of questions 3 and 6 oct/nov 2009 paper 32
I attached the paper so you can download it! :)
Thank you so much <3
« Last Edit: January 26, 2011, 08:26:39 pm by melony »
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Offline melony

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #103 on: January 29, 2011, 04:05:02 pm »
ok i managed to solve 3 PLEASE HELP WITH 6!!! :(
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elemis

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #104 on: January 30, 2011, 04:33:00 pm »
Quote from: melony on January 29, 2011, 04:05:02 pm
ok i managed to solve 3 PLEASE HELP WITH 6!!! :(

I really dont know.
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