Author Topic: C3 and C4 DOUBTS HERE!!!  (Read 36145 times)

**RoRo**

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Re: C3 and C4 Doubts Here!!!
« Reply #75 on: April 05, 2011, 02:18:36 pm »
Do we have to memorize the expansions of Sin(A+B), Cos(A+B), CosA CosB- SinA Sin B or they'll be given in the formula booklet?
Also does anyone know a helpful website to help me in chapters 6 and 7? (tirgnometry)

They'll be given to you in the formula booklet.
Check this site: http://www.trigonometry-help.net/

Offline Arissa_04

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Re: C3 and C4 Doubts Here!!!
« Reply #76 on: April 05, 2011, 06:10:08 pm »
Hey guys, need help in a trig question.not sure which year it is is from.Here's how the question goes:

Using the expansion of cos(3x-x) and cos(3x+x) prove that:

                    1/2(cos2x - cos4x) = sin3x sinx

Its a 3 mark question so I'm pretty sure its not that complicated but I cant seem to get the answers.
Thanks in advance Smiley

Offline mdwael

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Re: C3 and C4 Doubts Here!!!
« Reply #77 on: April 06, 2011, 10:50:51 am »
Anyone got a link or could upload the formula booklet which is provided when you do the Maths Edexcel exam?
"We all want to be different, which makes us all the same"

**RoRo**

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Re: C3 and C4 Doubts Here!!!
« Reply #78 on: April 06, 2011, 05:12:12 pm »
Anyone got a link or could upload the formula booklet which is provided when you do the Maths Edexcel exam?

I had asked the same question on Page 3, there you go with the link:
http://www.edexcel.com/migrationdocuments/GCE%20New%20GCE/N38210A-GCE-Mathematical-Formulae-Statistical-Tables.pdf

**RoRo**

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Re: C3 and C4 Doubts Here!!!
« Reply #79 on: April 30, 2011, 09:33:50 am »
Can someone please explain to me how do you part b and c?

Offline astarmathsandphysics

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Re: C3 and C4 Doubts Here!!!
« Reply #80 on: April 30, 2011, 10:00:55 am »
Complete the square for the numerator to get (x+1/2)^2+3/4>=3/4

Offline Aadeez || Zafar

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Re: C3 and C4 Doubts Here!!!
« Reply #81 on: April 30, 2011, 10:08:06 am »
b)

let x2+x+1 be equal to y
y = x2+x+1
  = x2+x+.25+.75
 = (x+.5)2+.75
 
there fore (x+.5)2 is a positive number and so .75 added to positive number gives positive number

and so

y is positive
therefore y>0
=x2+x+1>0

C)2+x+1 is positive and (x+2)2 is positive so positve number divided by positive is positive and so f(x) is positive

so therefor f(x)>0



Yeh BaaabuRaao ka style hein!

**RoRo**

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Re: C3 and C4 Doubts Here!!!
« Reply #82 on: April 30, 2011, 10:21:48 am »
b)

let x2+x+1 be equal to y
y = x2+x+1
  = x2+x+.25+.75
 = (x+.5)2+.75
 
there fore (x+.5)2 is a positive number and so .75 added to positive number gives positive number

and so

y is positive
therefore y>0
=x2+x+1>0

C)2+x+1 is positive and (x+2)2 is positive so positve number divided by positive is positive and so f(x) is positive

so therefor f(x)>0

Okay, thank you very much! :D

Offline Blizz_rb93

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Re: C3 and C4 Doubts Here!!!
« Reply #83 on: May 31, 2011, 12:01:44 pm »
f(x) = x + 3/x-1 - 12/x^2 + 2x -3  [x is an element of all eral number, x>1]

Show that f(x) = x^2 + 3x + 3 / x+3

in the book page 11 mixed exercise 1e q4

Thank you

Offline thenewkid™

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Re: C3 and C4 Doubts Here!!!
« Reply #84 on: June 08, 2011, 11:15:14 pm »
anybody have any revision notes or pointers?
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Offline thenewkid™

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Re: C3 and C4 Doubts Here!!!
« Reply #85 on: June 08, 2011, 11:15:45 pm »
anybody have any revision notes or pointers?
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Offline deadlyelder

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Re: C3 and C4 Doubts Here!!!
« Reply #86 on: June 10, 2011, 06:43:49 am »
Have attached the C3 Revision Sheet from http://www.r9paul.org/resources/a-level/ check the site for more notes on M1, M2, Physics, Computing and Religion Studies. They are quite handy notes.

Cheers
« Last Edit: June 10, 2011, 06:46:53 am by deadlyelder »

Offline thenewkid™

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Re: C3 and C4 Doubts Here!!!
« Reply #87 on: June 11, 2011, 02:07:06 pm »
THANKS :D
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Offline studz

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Re: C3 and C4 Doubts Here!!!
« Reply #88 on: June 12, 2011, 06:31:12 pm »
guys how are the last three chapters of c3 coming up for u all?
i am having  alot of difficulty studying those last 3 chapters!  :'(
any tips on how to get those chapters in my head? :/
i did those 3 chapters from the book twice but i still cant get them in my head!!  :-\ :-[ :'(
could've would've should've....BUT DIDN'T!

Offline thenewkid™

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Re: C3 and C4 Doubts Here!!!
« Reply #89 on: June 13, 2011, 06:53:50 pm »
those chaps are plain nightmares, the only way out is practice   :-\
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