Edexcel A2 C4 Mathematics June 2016 - Official Thread

How's everyone revising for C4 (and C3) at this moment in time? Just past papers?

I might do the all the Solomon papers for each one

Reply 2501

joodaa

5

Original post by Serine Soul

It's on the C3 spec :dontknow:

Ooo its come up on a paper i'm doing and my teachers never even mentioned it

Reply 2502

Don Pedro K.

9

@SeanFM what's proving by counterexample?

Reply 2503

Don Pedro K.

9

Original post by particlestudent

How's everyone revising for C4 (and C3) at this moment in time? Just past papers?

I might do the all the Solomon papers for each one

Past papers are the way to go :biggrin:

!

Reply 2504

particlestudent

13

Original post by Don Pedro K.

Past papers are the way to go :biggrin:

!

I'm nervous for C4... C3 isn't too bad but because the M1 exam went well, it makes it slightly better

Reply 2505

samb1234

13

Original post by Don Pedro K.

@SeanFM what's proving by counterexample?

Stupid person: 'i think every number is odd'
you: 'but what about 2,4 and 6'
Stupid person 'oh yeah'

Reply 2506

Kevin De Bruyne

21

Original post by joodaa

Ooo its come up on a paper i'm doing and my teachers never even mentioned it

Original post by Don Pedro K.

@SeanFM what's proving by counterexample?

Best person to ask is someone doing it in a paper :tongue:

never bothered learning it in C3 (didn't know it existed, or if I did I wouldn't know it by name) and don't really remember it from first year uni stuff :hide:

I guess contradicting a statement works.

Reply 2507

Don Pedro K.

9

Original post by particlestudent

I'm nervous for C4... C3 isn't too bad but because the M1 exam went well, it makes it slightly better

I'm more confident with C4 than C3 hah xD

Original post by samb1234

Stupid person: 'i think every number is odd'
you: 'but what about 2,4 and 6'
Stupid person 'oh yeah'

Ahh I thought as much haha! Nice explanation :wink:

Reply 2508

joodaa

5

Original post by SeanFM

Best person to ask is someone doing it in a paper :tongue:

never bothered learning it in C3 (didn't know it existed, or if I did I wouldn't know it by name) and don't really remember it from first year uni stuff :hide:

I guess contradicting a statement works.

Ah cheers lad is there any other insertname examples or is counterexample the only one?

Reply 2509

particlestudent

13

Original post by Don Pedro K.

I'm more confident with C4 than C3 hah xD

Really? I think I understand C4 more but because pretty much every question is a whole page of working out, I make far too many mistakes.

Reply 2510

Don Pedro K.

9

Original post by particlestudent

Really? I think I understand C4 more but because pretty much every question is a whole page of working out, I make far too many mistakes.

Yeah haha I'm surprised but happy about it ;p! I guess it just comes down to practice so that you make as few mistakes as possible!

Reply 2511

Kevin De Bruyne

21

Original post by joodaa

Ah cheers lad is there any other insertname examples or is counterexample the only one?

There's another one where you prove something to be true by showing that if it is false, there is something wrong... but I really don't think something like that would be expected of you, unless it was fairly easy/straightforward.

Reply 2512

Zacken

22

Original post by smackitintheair

What kind of method marks did you miss out on? I thought usually if you get the final answer correct you get all the marks

I got the correct answer but missed out marks because it wasn't in the uglier(!) form specified by the question so dropped one raw mark and hence 2 UMS marks.

Reply 2513

cookiemonster15

17

For C4, do we have to know the intergration of a^x? I thought we only needed to know how to differentiate it but it's come up on question 5d on the Jan 2013 paper (I think it also came up in the 2015 one?)

Can someone please show me how you would integrate it? I tried to use substitution (I think I set it equal to y) and then subbed the value back into my final answer but I'm not sure if this is completely correct?

Reply 2514

Don Pedro K.

9

Original post by cookiemonster15

For C4, do we have to know the intergration of a^x? I thought we only needed to know how to differentiate it but it's come up on question 5d on the Jan 2013 paper (I think it also came up in the 2015 one?)

Can someone please show me how you would integrate it? I tried to use substitution (I think I set it equal to y) and then subbed the value back into my final answer but I'm not sure if this is completely correct?

Well, I haven't seen anything like this before but I think I may know how to do it.

So we know that when y = 2^x for example, dy/dx = 2^xln2 (you should know how to derive this also using implicit differentiation).

Now integrating is basically seeing how to go from "dy/dx" back to your "y". So if we have integrating 2^x, and we know that dy/dx = 2^xln2, what do we need to do to 2^xln2 in order to get just 2^x? That's right, times 2^xln2 by 1/ln2 so that the "ln2" cancels out.

Therefore, integrating 2^x gives 2^x * 1/ln2 + c ----> 2^x/ln2 + c.

There's probably a better explanation for this but this is my thought process :s-smilie:

!

Reply 2515

Don Pedro K.

9

Original post by cookiemonster15

For C4, do we have to know the intergration of a^x? I thought we only needed to know how to differentiate it but it's come up on question 5d on the Jan 2013 paper (I think it also came up in the 2015 one?)

Can someone please show me how you would integrate it? I tried to use substitution (I think I set it equal to y) and then subbed the value back into my final answer but I'm not sure if this is completely correct?

This video shows an actual proof as to how to go about doing these types of questions ^_^ https://www.youtube.com/watch?v=JVIzBYGH1gQ

Reply 2516

candol

7

Original post by cookiemonster15

For C4, do we have to know the intergration of a^x? I thought we only needed to know how to differentiate it but it's come up on question 5d on the Jan 2013 paper (I think it also came up in the 2015 one?)

Can someone please show me how you would integrate it? I tried to use substitution (I think I set it equal to y) and then subbed the value back into my final answer but I'm not sure if this is completely correct?

They seem to like asking this type of question a bit more in recent years. You need to think about reverse of differentiation (recognition) when answering these types of questions
ie you know a^x differentiates to a^x lna
so integrating a^x must go to (a^x)/lna (since you are lacking that constant had you differentiated a^x)

Reply 2517

Engineerrookie

2

What should I be getting in C4 and C3 past papers average to get an A* in the. Actual exam?

Reply 2518

Kevin De Bruyne

21

Original post by Engineerrookie

What should I be getting in C4 and C3 past papers average to get an A* in the. Actual exam?

C3... maybe 72/75, around that.

C4... 67+ I guess, because it's more difficult.

At least, that is what I was averaging as far as I can remember :tongue:

Reply 2519

Don Pedro K.

9

Original post by SeanFM

C3... maybe 72/75, around that.

C4... 67+ I guess, because it's more difficult.

At least, that is what I was averaging as far as I can remember :tongue:

Sean, do you think we would be expected to be able to integrate something like (x)(5^{-x^2})?

Edexcel A2 C4 Mathematics June 2016 - Official Thread

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