You are Here: Home >< Maths

# Edexcel C4 Revision Thread (28/06 14:00) watch

1. (Original post by endeavour)
Do you just want help with the differentiation?

M = 10(0.98)t
lnM = ln10 + tln0.98

differentiating implicitly wrt t:
(1/M)(dM/dt) = ln0.98
dM/dt = M ln0.98
thanks. i didnt actually get what the question meant and what i was supposed to do.
2. (Original post by TheWolf)
What new formulas (other than c3 ones) do we need to learn? I find the half angle ones v.useful.
I have made a list of integrals for C4 (link) and other than those you need to know:

-- Scalar Product Formula

-- Angle between two Vectors (rearrangement of SP formula)

-- Separation of Variable Formula (not a formula as such)

-- Volume Formula (again not really a formula)

-- Double Angle Formulae (V. Useful as you say)

That is it.

So basically: nothing.
3. (Original post by nas7232)
can someone do this question for me

evaluate
∫[2/(x-3)] - [1/(x+4)] ∂x

Between 2 and 0

plz do u have answers to mock c4 that u offer????

if so plz send it to me on my mail : [email protected]
4. (Original post by ABUSHOMAL///M3)
plz do u have answers to mock c4 that u offer????

if so plz send it to me on my mail : [email protected]

http://www.thestudentroom.co.uk/show...9&postcount=25
http://www.thestudentroom.co.uk/show...9&postcount=35
http://www.thestudentroom.co.uk/show...9&postcount=44

and now:

http://www.thestudentroom.co.uk/show...9&postcount=63

All people requesting the mock paper solutions.

Is there an official mark scheme? I don't think so.

I am yet to do the paper myself, but when I do (tomorrow) I think I will type up my answers (not the mark scheme just the numbers) to help all of you folk out.

In the meantime why don't any of you do the same and then compare and constrast.
5. just started my c4 revision and this has got to b the best thread ever

i The Wolf

thanks all
6. it says edexcel praccies file is invalid or currupted

how close r the zigzag ones to the syllabus cos they work
7. Here is a very basic integration by substitution question but I'm not sure what I'm doing.

(1 + sinx)/cosx)dx ; u = sinx
8. (Original post by ntrik)
Here is a very basic integration by substitution question but I'm not sure what I'm doing.

(1 + sinx)/cosx)dx ; u = sinx
any limits?

integrate with respect to u

du/dx = cosx
dx = du/cosx

x= arcsin u

substitute that in
9. (Original post by nas7232)
any limits?

integrate with respect to u

du/dx = cosx
dx = du/cosx

x= arcsin u

substitute that in
No limits. Where would you substitute x = arcsin u? in both sinx and cosx?
10. (Original post by ntrik)
Here is a very basic integration by substitution question but I'm not sure what I'm doing.

∫((1 + sinx)/(cosx))dx ; u = sinx
∫((1 + sinx)/(cosx))dx = I

du/dx = cosx

dx/du = 1/cosx

dx = (1/cosx)du

So when the dx is replaced you'll get cos²x on the bottom.

Find cos²x in terms of u.

cos²x = 1 - sin²x = 1 - u²

So: I = ∫(1 + u)/(1 - u²)du

I = ∫(1 + u)/(1 + u)(1 - u)du (diff of 2 squares)

I = ∫1/(1 - u)du

I = -ln(1 - u) + C

I = -ln(1 - sinx) + C

EDIT: making it correct.
11. (Original post by samdavyson)
So: I = ∫(u)/(1 - u²)du
Thanks, I got your pm but at this point, isn't it I = ∫(1 + u)/(1 - u²)du ?
12. hey guys~ kinda stuck in Jan 2002 Q.8 part (c). can't figure out the area of the parallelogram~0_0..help plz~
13. (Original post by ntrik)
Thanks, I got your pm but at this point, isn't it I = ∫(1 + u)/(1 - u²)du ?
Sorry at that point I was thinking 1 + sinx = u.

I have corrected the post above.
14. (Original post by im37)
hey guys~ kinda stuck in Jan 2002 Q.8 part (c). can't figure out the area of the parallelogram~0_0..help plz~
What is that Jan 02 P3?
15. (Original post by samdavyson)
What is that Jan 02 P3?
yes, forget to specify
16. (Original post by im37)
yes, forget to specify
Umm.

Parallelogram has area 1/2 x base x height.

You find the base and height lengths from the equations of the normals to the ellipse at the given values of the parameter.

(You will only need to do one normal due to the symmetry).

17. i see wt u mean, but i dunno how to find the lengths of base & height in this case....
18. (Original post by im37)
i see wt u mean, but i dunno how to find the lengths of base & height in this case....
Find equations of normals.

Sub in y = 0 for x axis intersection, and x = 0 for y axis intersection.

Times both values by 2.

These are the base and height.
19. thx alot~ i got it!
20. there is an official mark shecem for the mock , ill scan it in later today and post it, prob in the evenin say 11ish

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: June 28, 2005
The home of Results and Clearing

### 3,197

people online now

### 1,567,000

students helped last year
Today on TSR

Hang on, have Edexcel's come out already?

### University open days

1. SAE Institute
Animation, Audio, Film, Games, Music, Business, Web Further education
Thu, 16 Aug '18
2. Bournemouth University
Fri, 17 Aug '18
3. University of Bolton
Fri, 17 Aug '18
Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams