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Edexcel A2 C3 Mathematics 12th June 2015

Reply 1540

Humbers

2

Original post by ridirahman

How would you draw that??
I need to draw it to find the domain

You cant really find the domain from a graph in this case, you'd need to know to use common sense that ln(x+2) x+2 cannot be zero as ln0 is undefined

Reply 1541

Ripper Phoenix

17

Original post by kdevitto

http://qualifications.pearson.com/content/dam/pdf/A%20Level/Mathematics/2013/Exam%20materials/6665_01_msc_20100218.pdf

Question 8 here, why does cot2x=0 become tan2x= infinity symbol?
Could someone explain how they solved this? Thanks!

simple! cot 2x is the same as cos2x/sin2x.

So eventually cos2x=0 AND YOU SOLVE!! :smile:

YOU WILL GET 90,270

Reply 1542

Kevin De Bruyne

21

Original post by domcandrews

https://b3755649dbd1afe3db91a899c3b9837b22326254.googledrive.com/host/0B1ZiqBksUHNYMG14YWtobVJUUms/for-Edexcel/Solomon%20G%20QP%20-%20C3%20Edexcel.pdf

Anyone help on Q2 part b, not sure where they're getting the solution from/what to use

MS is here:
https://b3755649dbd1afe3db91a899c3b9837b22326254.googledrive.com/host/0B1ZiqBksUHNYMG14YWtobVJUUms/for-Edexcel/Solomon%20G%20MS%20-%20C3%20Edexcel.pdf

many thanks

i'm guessing you got to cos(2x+(2pi/3)) = 1/2.

Since you're looking for solutions in the range 0<x<pi, if we call 2x+(2pi/3) theta, then the range of theta is 2pi/3 < theta < 8pi/3. At this point you may wish to use a CAST diagram and find all the values, and pick out the ones in the range before finding the x values.

Reply 1543

Ripper Phoenix

17

Original post by BioAgent

For the Rcosalpha/Rsinalpha questions do you have to show all your working?

why risk it? show all working! :smile:

Reply 1544

frozo123

12

Original post by domcandrews

count me in too, started today and haven't looked at c3 since we finished it back in november, this is going to be fun loooool

Nah I'm messing up the studentroom's high scoring pattern

Reply 1545

Cosmi

2

Original post by kdevitto

http://qualifications.pearson.com/content/dam/pdf/A%20Level/Mathematics/2013/Exam%20materials/6665_01_msc_20100218.pdf

Question 8 here, why does cot2x=0 become tan2x= infinity symbol?
Could someone explain how they solved this? Thanks!

cot = cos/sin

cos = 0

2x = cos-1(0)

Reply 1546

domcandrews

2

Original post by Ripper Phoenix

Youll be relieved that proving by counter and stuff isnt on edexcel syllabus. Edexcel can not bring stuff outside the spec. It would result in a petition. But anyway good luck 👌🏼

Posted from TSR Mobile

Ah thank you! I wouldn't have known, but it's not that bad actually but cheers for the heads up!

Reply 1547

Mrkingpenguin

18

Anyone got the jan 2015 ial paper?

Reply 1548

domcandrews

2

Original post by frozo123

Nah I'm messing up the studentroom's high scoring pattern

AHAHA yesss

Reply 1549

Cosmi

2

Original post by Cosmi

http://www.examsolutions.net/a-level-maths-papers/worked-solution/worked-solution.php?paper_id=96&solution=8.2

Why isn't cos() -1? Surely -21/25 is smaller than 21/25?

Anyone able to help with this? I've never understood this. :s-smilie:

Reply 1550

Maham88

2

Original post by Mrkingpenguin

Anyone got the jan 2015 ial paper?

https://drive.google.com/folderview?id=0B1ZiqBksUHNYak5FZDJHS1ZSTHM#list

Reply 1551

MATTTT

2

How THE FUDGE is part a (i) the graph of f^-1(x) ?

i thought to draw the inverse function you reflect the f(x) in the y=x line.
Rather than imagining it through the head, is it possible to just times the co-ordinates by something to find the reflection in the y=x line Because i do not understand how they got that in part a (i)

Someone help!

Screen Shot 2015-06-11 at 6.26.03 PM.png100.9KB

Reply 1552

SuperMushroom

9

Original post by Mrkingpenguin

Anyone got the jan 2015 ial paper?

https://drive.google.com/folderview?id=0B1ZiqBksUHNYak5FZDJHS1ZSTHM

Reply 1553

studentwiz

3

Original post by Humbers

I feel like a butchered the answer but i got there in the end, if theres a quicker way that i missed, tell me :biggrin:

Original post by Ripper Phoenix

ImageUploadedByStudent Room1434042359.773889.jpg

Posted from TSR Mobile

thanks guys

Reply 1554

Cosmi

2

Original post by Mrkingpenguin

Anyone got the jan 2015 ial paper?

https://drive.google.com/folderview?id=0B1ZiqBksUHNYak5FZDJHS1ZSTHM#list

Think they combine c3/c4

Reply 1555

domcandrews

2

Original post by SeanFM

i'm guessing you got to cos(2x+(2pi/3)) = 1/2.

Since you're looking for solutions in the range 0<x<pi, if we call 2x+(2pi/3) theta, then the range of theta is 2pi/3 < theta < 8pi/3. At this point you may wish to use a CAST diagram and find all the values, and pick out the ones in the range before finding the x values.

Nope i don't understand how they got to that first bit with cos(2x + 2pi/3)??? Am i missing something silly or...?

Reply 1556

Ripper Phoenix

17

Original post by Mrkingpenguin

Anyone got the jan 2015 ial paper?

its a c34 paper not a c3 paper on its own

Reply 1557

Myuna

1

Original post by studentwiz

someone help

Reply 1558

Kevin De Bruyne

21

Original post by domcandrews

Nope i don't understand how they got to that first bit with cos(2x + 2pi/3)??? Am i missing something silly or...?

It's linked to part a. Sec(x+(pi/6)) is the same as 1/(cos(x+(pi/6)), so they've multiplied both sides by cos(x+(pi/6)) to get something of the form in part a.

Reply 1559

MATTTT

2

How the FUDGE is part a (i) the graph of the inverse function? i thought the inverse function is a reflection in y=x line and i just can't see that with this graph in my head.
Is there a way in which you can just times the co-ordinates by something to find the reflection in the y=x line??? Someone please help!

Screen Shot 2015-06-11 at 6.26.03 PM.png100.9KB

Edexcel A2 C3 Mathematics 12th June 2015

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