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Author Topic: C1 and C2 DOUBTS HERE!!!!!  (Read 93571 times)

Alpha

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Re: C2 DOUBTS HERE!!!!!
« Reply #180 on: June 07, 2010, 05:49:35 pm »
V > 0.

Ya, I got you. Inequalities.
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Offline halosh92

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Re: C2 DOUBTS HERE!!!!!
« Reply #181 on: June 07, 2010, 05:55:02 pm »
Quote from: ~Alpha on June 07, 2010, 05:49:35 pm
V > 0.

Ya, I got you. Inequalities.

but the ms says:

0<x<20
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everyday we wake up is a miracle, then how do we say miracles dont happen?????

Alpha

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Re: C2 DOUBTS HERE!!!!!
« Reply #182 on: June 07, 2010, 06:17:21 pm »
Quote from: halosh92 on June 07, 2010, 05:55:02 pm
but the ms says:

0<x<20

Okay, I guess Dude eliminated the 4x.

4x(x - 25)(x - 20) > 0

3 critical values:

x = 0, x = 20, x = 25.

V = 4x(x - 25)(x - 20)
As x tends to infinity; V tends to infinity.
As x tends to -ve infinity; V tends to -ve infinity.

See the curve in the attachment.

V > 0; upper part lying above the line.

Therefore, 0 < x < 20, and x > 25.

Now, why is x > 25 eliminated...
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Alpha

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Re: C2 DOUBTS HERE!!!!!
« Reply #183 on: June 07, 2010, 06:19:56 pm »
Ah yes, the file...
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Offline halosh92

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Re: C2 DOUBTS HERE!!!!!
« Reply #184 on: June 07, 2010, 06:25:31 pm »
Quote from: ~Alpha on June 07, 2010, 06:17:21 pm
Okay, I guess Dude eliminated the 4x.

4x(x - 25)(x - 20) > 0

3 critical values:

x = 0, x = 20, x = 25.

V = 4x(x - 25)(x - 20)
As x tends to infinity; V tends to infinity.
As x tends to -ve infinity; V tends to -ve infinity.

See the curve in the attachment.

V > 0; upper part lying above the line.

Therefore, 0 < x < 20, and x > 25.

Now, why is x > 25 eliminated...

ure amazing thankyou so much :D
maybe the ms is wrong those are just practice papers.. ;)
and thx to engraved also :D
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everyday we wake up is a miracle, then how do we say miracles dont happen?????

Alpha

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Re: C2 DOUBTS HERE!!!!!
« Reply #185 on: June 07, 2010, 06:26:29 pm »
Oh yeah.  ;D

I'm getting tired today...

Length is 50. x is being cut from both sides. Logically, x cannot be greater than 25: you cannot cut longer than the length.  ;)
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Alpha

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Re: C2 DOUBTS HERE!!!!!
« Reply #186 on: June 07, 2010, 06:28:01 pm »
Quote from: halosh92 on June 07, 2010, 06:25:31 pm
ure amazing thankyou so much :D
maybe the ms is wrong those are just practice papers.. ;)
and thx to engraved also :D

Welcome that much.   ;)

Thank you Dude too, much appreciated. He helps a lot here.

Nah, MS is right.  ;)
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Offline Saladin

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Re: C2 DOUBTS HERE!!!!!
« Reply #187 on: June 07, 2010, 06:32:28 pm »
Quote from: ~Alpha on June 07, 2010, 06:28:01 pm
Welcome that much.   ;)

Thank you Dude too, much appreciated. He helps a lot here.

Nah, MS is right.  ;)

Thank you for your appreciaton, which Qual do you do, Edexcel or CIE?
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Alpha

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Re: C2 DOUBTS HERE!!!!!
« Reply #188 on: June 07, 2010, 06:35:09 pm »
CIE, A Level for Maths, Pure Maths, HSC Cambridge.

How about you?
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Offline halosh92

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Re: C2 DOUBTS HERE!!!!!
« Reply #189 on: June 07, 2010, 07:41:50 pm »
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everyday we wake up is a miracle, then how do we say miracles dont happen?????

Offline Saladin

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Re: C2 DOUBTS HERE!!!!!
« Reply #190 on: June 07, 2010, 07:44:24 pm »
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Offline Ghost Of Highbury

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Re: C2 DOUBTS HERE!!!!!
« Reply #191 on: June 07, 2010, 07:51:04 pm »
U just gotta plot the graph correctly.

(b) can be done by lookin at the graph itself..check for the highest and lowest points, and rite em down,

(c) f(x) = 2.5 means

y = 2.5

5sin 3x = 2.5

sin 3x = 1/2 ..say (a = 3x)

sin a = 0.5

a = (sin)-1 0.5 = 30

a = 3x =  30

x = 10

3x = 180-30 = 150

x = 50

3x = 360+30 = 390

x = 130

---b = 3x-----
b = 150

b= 360+150 = 510

3x = 510

x = 170



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Offline halosh92

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Re: C2 DOUBTS HERE!!!!!
« Reply #192 on: June 07, 2010, 07:58:39 pm »
Quote from: Ghost Of Highbury~ on June 07, 2010, 07:51:04 pm
U just gotta plot the graph correctly.

(b) can be done by lookin at the graph itself..check for the highest and lowest points, and rite em down,

(c) f(x) = 2.5 means

y = 2.5

5sin 3x = 2.5

sin 3x = 1/2 ..say (a = 3x)

sin a = 0.5

a = (sin)-1 0.5 = 30

a = 3x =  30

x = 10

3x = 180-30 = 150

x = 50

3x = 360+30 = 390

x = 130

---b = 3x-----
b = 150

b= 360+150 = 510

3x = 510

x = 170





thankyou very much :D
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everyday we wake up is a miracle, then how do we say miracles dont happen?????

Offline halosh92

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Re: C2 DOUBTS HERE!!!!!
« Reply #193 on: June 07, 2010, 08:32:11 pm »
same paper Q8iia
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everyday we wake up is a miracle, then how do we say miracles dont happen?????

Offline Saladin

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Re: C2 DOUBTS HERE!!!!!
« Reply #194 on: June 07, 2010, 08:43:36 pm »
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