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Author Topic: [CIE] All Pure Mathematics (P1, P2 and P3) doubts here !  (Read 77874 times)

Offline melony

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #105 on: February 02, 2011, 02:13:49 pm »
Quote from: Ari Ben Canaan on January 30, 2011, 04:33:00 pm
I really dont know.

thanx for havn a look though
thats very considerate of you  :)
« Last Edit: February 02, 2011, 02:17:26 pm by melony »
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elemis

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #106 on: February 02, 2011, 02:30:27 pm »
Quote from: melony on February 02, 2011, 02:13:49 pm
thanx for havn a look though
thats very considerate of you  :)

The forum is pretty dead right now.

I'd suggest asking your teacher or a friend.
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Offline S.M.A.T

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #107 on: February 02, 2011, 10:32:15 pm »
Quote from: melony on January 29, 2011, 04:05:02 pm
ok i managed to solve 3 PLEASE HELP WITH 6!!! :(

Here
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Offline yasser37

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #108 on: February 03, 2011, 07:26:45 am »
can someone please tell me what the product rule is?  :-[ :-[
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Offline Deadly_king

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #109 on: February 03, 2011, 07:57:15 am »
Quote from: yasser37 on February 03, 2011, 07:26:45 am
can someone please tell me what the product rule is?  :-[ :-[

Okay......i'll take an example to explain it.

Let's say you're given y = x(x+1) and you're asked to differentiate using the product rule.

Product rule = dy/dx = u.dv/dx + v.du/dx

In this case u = x and v = x+1

So du/dx = 1 and dv/dx = 1

Now you replace in the formula of the product rule to get dy/dx = x(1) + (x+1)(1) = 2x + 1

Hope it helps :D
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Offline yasser37

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #110 on: February 03, 2011, 08:20:53 am »
thanks man

appreciated
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Offline Deadly_king

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #111 on: February 03, 2011, 09:38:38 am »
Quote from: yasser37 on February 03, 2011, 08:20:53 am
thanks man

appreciated

You're welcome buddy :)
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Offline aloha32

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #112 on: February 21, 2011, 01:29:41 pm »
Hello
This is a question from P3 Nov 2002
Please help!
The curve y= e^x + 4e^-2x has one stationary point. Find the x coordinate of the stationary point and determine whether it is max or min

I differentiated the equation and got till e^x - 8e^-2x and equated it to zero but I'm stuck from there.
It'd be great if someone could guide me

Thanks! :)
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Offline Monopoly

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #113 on: March 05, 2011, 03:11:35 pm »
Quote from: aloha32 on February 21, 2011, 01:29:41 pm
Hello
This is a question from P3 Nov 2002
Please help!
The curve y= e^x + 4e^-2x has one stationary point. Find the x coordinate of the stationary point and determine whether it is max or min

I differentiated the equation and got till e^x - 8e^-2x and equated it to zero but I'm stuck from there.
It'd be great if someone could guide me

Thanks! :)


e^x - 8e^-2x can also be written as (e^3x -8)/e^2x
Equate this to zero and u will get e^3x = 8 and then solve for x
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Offline Monopoly

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #114 on: March 05, 2011, 03:14:13 pm »
I need help with question number 7(iii), paper 3 of may/june 2010, variant 1
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Offline thecandydoll

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #115 on: March 06, 2011, 03:05:30 am »
How do we binomially expand using differentiation?
It says in the marskschemes,but i dont get it :D
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Offline yasser37

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #116 on: March 11, 2011, 03:32:06 pm »
November 09
p31
question 4
question 10
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elemis

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #117 on: March 16, 2011, 02:55:37 pm »
Quote from: yasser37 on March 11, 2011, 03:32:06 pm
November 09
p31
question 4
question 10


10 minutes.
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elemis

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #118 on: March 16, 2011, 03:05:11 pm »
u=e-3x

v=tanx

du/dx = -3e-3x

dv/dx = sec2x

Hence,

dy/dx = e-3xsec2x -3e-3xtanx

e-3x(sec2x - 3tanx)

Using 1+tan2x=sec2x

e-3x(tan2x - 3tanx + 1)

Solve the part in bold as a normal quadratic equation to give :

x = 1.206,0.365
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elemis

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Re: All Pure Mathematics DOUBTS HERE!!!
« Reply #119 on: March 16, 2011, 03:11:09 pm »
dA/dt = 4/3*k*\pir3

dA/dr = 8\pir

This should be simple to solve now.
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