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# Edexcel A2 C4 Mathematics June 2015 - Official Thread watch

1. (Original post by tiny hobbit)
Remember that m is a constant so it's like integrating (7x)^2 i.e. 49x^2

Have you already written m in terms of h and r?
Yes, thank you, I've done it now
2. Can someone guide me what to do.
What limits do I use when I integrate y=1/2t^3+3 . dx/dt. dt?

How do I use the info that a line has the equation x = 1?
Attached Images

3. (Original post by XxKingSniprxX)
Can someone guide me what to do.
What limits do I use when I integrate y=1/2t^3+3 . dx/dt. dt?

How do I use the info that a line has the equation x = 1?
Split R into two regions either side of P. Note that on the RHS you have a triangle, and on the LHS you only have the curve C, which you can integrate parametrically.
4. I need help or guidance on how to answer B please.

For Part A I got: A(-3, 4) and B(3,4)

For Part B, I got 132.pi and the answer in the book says 36.pi. Can someone tell me if whether I'm wrong or is the
Attached Images

5. (Original post by XxKingSniprxX)
Can someone guide me what to do.
What limits do I use when I integrate y=1/2t^3+3 . dx/dt. dt?

How do I use the info that a line has the equation x = 1?
Your limits are the t values at each end of the bit of curve because it is "dt". You are told that the t value at P is 2. You need to convert x = 1 into a t value for your lower limit.

I don't like the way it says that the normal cuts the x axis at t = 3, since that point isn't on the curve. I assume they just mean x = 4^2 = 16
6. (Original post by XxKingSniprxX)

For Part A I got: A(-3, 4) and B(3,4)

For Part B, I got 132.pi and the answer in the book says 36.pi. Can someone tell me if whether I'm wrong or is the
Your answer is for all of the area below the circle being rotated round the x-axis. Your napkin ring needs a cylindrical hole in the middle. Its radius is the y coord and its height is from -3 to 3. Subtract that volume and you'll get the 36 pi.
7. I know this is a c3 question but would it be true to say:
Range of function = domain of inverse
Domain of function = range of inverse

??

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8. (Original post by clara16)
I know this is a c3 question but would it be true to say:
Range of function = domain of inverse
Domain of function = range of inverse

??

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yup its a rule
9. (Original post by clara16)
I know this is a c3 question but would it be true to say:
Range of function = domain of inverse
Domain of function = range of inverse

??

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however it looks better if i wrote:

range of inverse is equal to domain of function
domain of inverse is equal to range of function.

its basically the same as what you said but often in most cases you will have the range/ domain of the funtion and be asked to get the inverse then the domain/range of inverse.

10. (Original post by Paras Agarwal)
however it looks better if i wrote:

range of inverse is equal to domain of function
domain of inverse is equal to range of function.

its basically the same as what you said but often in most cases you will have the range/ domain of the funtion and be asked to get the inverse then the domain/range of inverse.

Thank you!

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11. What exactly is a Cartesian equation? I get incredibly confused with this, is it just removing t and combining both of them together? Sometimes I have no clue which one to start with too or how to approach them.

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12. (Original post by lam12)
What exactly is a Cartesian equation? I get incredibly confused with this, is it just removing t and combining both of them together? Sometimes I have no clue which one to start with too or how to approach them.

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A cartesian equation is basically one without a 't' in it. There's rarely one straight method to do it - could you give us an example of a problematic question?

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13. (Original post by ACarter8)
How long did the integration chapter take people to do?
Have you finished integration? We've covered everything except integration...

so how long would it take to completely learn everything about integration
in days or weeks?
thanksss
14. (Original post by PinkElephant16)
Have you finished integration? We've covered everything except integration...

so how long would it take to completely learn everything about integration
in days or weeks?
thanksss
A week of learning, at least 8hours & then a good 2 weeks of practice before i was 100% on it

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15. (Original post by clara16)
A week of learning, at least 8hours & then a good 2 weeks of practice before i was 100% on it

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wow I'm acc bricking it by practice do you mean textbook questions or?
16. (Original post by PinkElephant16)
wow I'm acc bricking it by practice do you mean textbook questions or?
I did most of the text book questions & some solomon worksheets then most of the exam questions. Its not as hard as it looks when you get your head around the different types of problem, the hardest bit is recognising which method to use

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17. People how are you revising/did you revise for S1? Will doing textbook and past papers be enough?

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18. (Original post by Senll)
People how are you revising/did you revise for S1? Will doing textbook and past papers be enough?

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I did loads of past papers and the international ones, I looked at the mark schemes consistently to make sure I was rounding correctly etc. I didn't really use the book much it was just pure past papers for me and I got an A :-) however my paper did get remarked from a B to an A so possibly first time marking they were harsh or just bad. Just really make sure you understand the knowledge well enough to adapt to curveballs etc. I revised quite late for it too as I kept forgetting stuff and currently d1 is a pain, but that's just me

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19. Is it me is or C4 harder than the other exams by quite a lot? :P
20. Ahh I see, I'm thinking of doing review exercises to get a grip on it first then attempt papers.

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