Edexcel C3,C4 June 2013 Thread

Original post by Zazuwaved

Hi,
I was wondering if anyone could help me with this kind of question

Given that x=3tan(2y-1), find dy/dx in terms of x

I normally work out the expression for dy/dx but then I struggle to put in terms of x?

Any help would be appreciated :biggrin:

im guessing you've got to

\frac{dy}{dx} = \frac{1}{6} cos^2(2y-1)

right? and they have given you

x = 3tan(2y-1)

okay? so rearrange it to get

2y-1

=

arctan \frac{x}{3}

and sub that into your dy/dx to get

\frac{dy}{dx} = \frac{1}{6} cos^2(arctan \frac{x}{3})

and there you go, it is interms of x

EDIT: reason why i knew how to do this, is because i usto struggle with this type of question before aswell, until my teacher helped me and showed me how to do it.

(edited 10 years ago)

Reply 1444

Zazuwaved

10

Original post by MedMed12

did a question just like this :tongue:

firstly differentiate to get dx/dy then do 1/dx/dy to get dy/dx
then depending on what you get you want to use the first equation give to be the same as that -if that makes sense. Look on exam solutions June 07 has the same style :smile:

did it today aha!

had cos(2y+6) intead of tan and differentiated to get -sin(2y+6) and then used the identity 1+sin^2 =cos^2 then did x/4 =sin(2y+6)

i know im making no sense, but use that video :smile:

i guess the question you have might use the identity which uses sec^2x

Thank you for reminding me about that paper, as I was doing the questions from the Edexcel book I forgot which paper I encountered that kind of question :biggrin:

Original post by masryboy94

im guessing you've got to

\frac{dy}{dx} = \frac{1}{6} cos^2(2y-1)

right? and they have given you

x = 3tan(2y-1)

okay? so rearrange it to get

2y-1

=

arctan \frac{x}{3}

and sub that into your dy/dx to get

\frac{dy}{dx} = \frac{1}{6} cos^2(arctan \frac{x}{3})

and there you go, it is interms of x

EDIT: reason why i knew how to do this, is because i usto struggle with this type of question before aswell, until my teacher helped me and showed me how to do it.

Thanks there mate, I had initially put that down as my answer, but when I looked at the back of the book (Edexcel's C3 Book) it had 3/2(9+x^2) as the answer so I was unsure as to whether putting it down as arctan(x) would be considered or not, thanks I wish there were more questions like this that I could practice from

thanks for your help :biggrin:

apparently it had something to do with converting sec^2(2y-1) into (1+tan^2(2y-1)) and using x/3=tan(2y-1) to sub in
:smile:

Reply 1445

Original post by Zazuwaved

Thank you for reminding me about that paper, as I was doing the questions from the Edexcel book I forgot which paper I encountered that kind of question :biggrin:

Thanks there mate, I had initially put that down as my answer, but when I looked at the back of the book (Edexcel's C3 Book) it had 3/2(9+x^2) as the answer so I was unsure as to whether putting it down as arctan(x) would be considered or not, thanks I wish there were more questions like this that I could practice from

thanks for your help :biggrin:

apparently it had something to do with converting sec^2(2y-1) into (1+tan^2(2y-1)) and using x/3=tan(2y-1) to sub in
:smile:

yeh both ways are correct !! your welcome :smile:

good luck !

Reply 1446

OP

Original post by masryboy94

...

Yo Masry and you other boys, I have returned from Ban-City or Ban-Ville.

Current Progression:
C3 - 9/11 Solomon Papers
C4 - 8/11 Solomon Papers.

Going to Step it up to 3 a Day so I can all my papers by around 2-5th June. Then re-do my Physics 4/5 and Chem 4/5 Papers.

Surprisingly my Maths has just jumped up a level, the Solomon have really increased my confidence in my Mathematical Ability - so thank you everyone for recommending.

I will make a big post of the my problems I had later on with images so people can help. Most of them were on C4 :/ The Solomon are sometimes so random.

Reply 1447

Original post by Better

Yo Masry and you other boys, I have returned from Ban-City or Ban-Ville.

Current Progression:
C3 - 9/11 Solomon Papers
C4 - 8/11 Solomon Papers.

Going to Step it up to 3 a Day so I can all my papers by around 2-5th June. Then re-do my Physics 4/5 and Chem 4/5 Papers.

Surprisingly my Maths has just jumped up a level, the Solomon have really increased my confidence in my Mathematical Ability - so thank you everyone for recommending.

I will make a big post of the my problems I had later on with images so people can help. Most of them were on C4 :/ The Solomon are sometimes so random.

nice !! im on 7/11 on both C3 and C4, gonna finish all soloman papers by end of monday ! that's my aim so 4 tomorrow and 4 after tomorrow. then do some past papers and then BANG OUT physics !! yeh same, my memories is refreshened for C3, thought i forgot it all ... haha yeh they are sometimes proper random :tongue:

Reply 1448

Kvothe the Arcane

20

Original post by Better

Yo Masry and you other boys, I have returned from Ban-City or Ban-Ville.

Current Progression:
C3 - 9/11 Solomon Papers
C4 - 8/11 Solomon Papers.

Going to Step it up to 3 a Day so I can all my papers by around 2-5th June. Then re-do my Physics 4/5 and Chem 4/5 Papers.

Surprisingly my Maths has just jumped up a level, the Solomon have really increased my confidence in my Mathematical Ability - so thank you everyone for recommending.

I will make a big post of the my problems I had later on with images so people can help. Most of them were on C4 :/ The Solomon are sometimes so random.

Welcome back Better. The majority of my exams are finished and I've started 0.5 term. I'm going to do all the Solomon papers over the next week.

Reply 1449

OP

Original post by masryboy94

nice !! im on 7/11 on both C3 and C4, gonna finish all soloman papers by end of monday ! that's my aim so 4 tomorrow and 4 after tomorrow. then do some past papers and then BANG OUT physics !! yeh same, my memories is refreshened for C3, thought i forgot it all ... haha yeh they are sometimes proper random :tongue:

Oh wow quality work as well! Yeah if you can do that, that would be great haha!! Let's do this bro!

Reply 1450

Original post by Better

Oh wow quality work as well! Yeah if you can do that, that would be great haha!! Let's do this bro!

hope its not all for nothing though !! im going to try my best. btw can you help me with the post i posted on page 72 its post no. 1438 ... thanks bro ! good luck :biggrin:

Reply 1451

OP

Original post by masryboy94

hope its not all for nothing though !! im going to try my best. btw can you help me with the post i posted on page 72 its post no. 1438 ... thanks bro ! good luck :biggrin:

Hmm. I'm not doing anything right now give me a second.

Edit: What paper is it from again? I keep my papers so I can look at my answer. I think I got the last bit wrong the first time I did it but I can re-do it and post

Reply 1452

Original post by Better

Hmm. I'm not doing anything right now give me a second.

Edit: What paper is it from again? I keep my papers so I can look at my answer. I think I got the last bit wrong the first time I did it but I can re-do it and post

tyt

... Paper E question 7)C)

Reply 1453

OP

Original post by masryboy94

tyt

... Paper E question 7)C)

Not sure its Paper E :s-smilie:

Was going to try to write it all up for you but its the wrong paper.

But basically its not as hard as you might initially think. It is translated by 10 to 70 which is a translation in x of -70.

You put this translation in the EXPONENT. And then use basic Power Rules. You were probably confused by the translation or the algebra.

Reply 1454

niki135

2

Original post by masryboy94

my advice for you at this moment of time which is what im doing with 2 weeks to C3 and 3 weeks to C4 is to JUST do soloman papers, forget doing past papers for now. honestly best advice i probably ever got from a friend of mine who did only soloman papers for the C3 january exam and got 97 UMS in the end. and to be time efficient, in the soloman papers if you are 100% sure that you can answer a question skip it and move on, do the challenging questions to help you notice your weaknesses. anything you might not understand you've got us here and you have exam solutions. VERY HELPFUL ! http://www.examsolutions.net/maths-revision/syllabuses/Edexcel/period-1/specification.php

dw you can get that grade you want !!! have faith in yourself. :biggrin:

Hey! Sorry for the late reply!

Wow really? I'm sorta scared of doing that, I feel like past papers are a must? But yes I will look through and do the Practice Papers (Papers A1-A6) I've got Biology and Chemistry too that I need to revise, so I can't spend too much time on C3/C4...

Thank you so much for the reply and the advice!! :smile:

Today I'm dedicating to C3/C4 and I might skim through those Solomon papers and pick out tough questions.
Better get back to it.
And yes I know I can do it, I just need to put in some solid work! Last thing I can do is panic, that never goes down well for me in maths...
THANK YOU once again for the kind words :jumphug:

Reply 1455

otrivine

14

Hi

can someone please check this solomon paper , I am not sure if there is a mistake or not but

http://www.school-portal.co.uk/GroupDownloadFile.asp?GroupId=1152243&ResourceId=3992058

http://www.school-portal.co.uk/GroupDownloadFile.asp?GroupId=1152243&ResourceId=3992046

question 4)a)

In the mark scheme , they got that for the integration and I got

1/3 In(x-6) - 1/3 In(x-3) = 2t + c

they put In(x-6) - In(x-3) = 6t +c

where does the 6 come from

thanks

Reply 1456

Original post by niki135

Hey! Sorry for the late reply!

Wow really? I'm sorta scared of doing that, I feel like past papers are a must? But yes I will look through and do the Practice Papers (Papers A1-A6) I've got Biology and Chemistry too that I need to revise, so I can't spend too much time on C3/C4...

Thank you so much for the reply and the advice!! :smile:

Today I'm dedicating to C3/C4 and I might skim through those Solomon papers and pick out tough questions.
Better get back to it.
And yes I know I can do it, I just need to put in some solid work! Last thing I can do is panic, that never goes down well for me in maths...
THANK YOU once again for the kind words :jumphug:

you shouldn't be scared, what is the difference between past papers and soloman papers? soloman papers are just more challenging hence when you do them and then decide to do a past paper you should feel its actually easier to do. in january exams i did all the C3 past papers and went into the exam confident, then two big mark questions put me off. funny thing is, those two questions were VERY similar to ones i found in the soloman papers. so think about it, right now best thing is solomans MY ADVICE. yeh i know what you mean i have 3 physics modules to do too and i NEED an A in it, plus i have my business exam, so there is a lot pressure, but dedicate your days now to JUST revising, and you will make it easily :biggrin:

... your welcome ! good luck dude :biggrin:

Reply 1457

thelion0

11

I've nearly finished C4 soloman, will then do normal papers, then elmwood , then delphis and finally zig-zag.

All questions in the C4 book are done including all the review exercises. I recommend others do the same.

Reply 1458

otrivine

14

Original post by masryboy94

you shouldn't be scared, what is the difference between past papers and soloman papers? soloman papers are just more challenging hence when you do them and then decide to do a past paper you should feel its actually easier to do. in january exams i did all the C3 past papers and went into the exam confident, then two big mark questions put me off. funny thing is, those two questions were VERY similar to ones i found in the soloman papers. so think about it, right now best thing is solomans MY ADVICE. yeh i know what you mean i have 3 physics modules to do too and i NEED an A in it, plus i have my business exam, so there is a lot pressure, but dedicate your days now to JUST revising, and you will make it easily :biggrin:

... your welcome ! good luck dude :biggrin:

Hello how are you :smile:

can you please check this solomon paper , I am not sure if there is a mistake or not but

http://www.school-portal.co.uk/Group...urceId=3992058

http://www.school-portal.co.uk/Group...urceId=3992046

question 4)a)

In the mark scheme , they got that for the integration and I got

1/3 In(x-6) - 1/3 In(x-3) = 2t + c

they put In(x-6) - In(x-3) = 6t +c

where does the 6 come from

thanks

Reply 1459