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OCR MEI C3 Maths June 2015

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Original post by Gcseboy1997
What points did we need for the graph? I only labelled one (-1, ln2)


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I can't remember exactly but I think it crossed the y axis at ln(3) I labelled that too but you'd have to look at past mark schemes to find out how the marks are awarded!
Original post by lizard54142
For the g(x) one the integral was the same as before, but negative so -(the one before). Don't think you said this on your mark scheme


I think I mentioned it, I just personally wasn't sure they wanted the negative result or not. I'll try and make my post more clear when I get home today thanks.
A couple of questions people, I'm really freaking out here. Please help.....

1) I wrote +0.5c in question 2 instead of +c
2) I wrote 4ln4 instead of ln 16 in question 2
3) i wrote 4ln4-1.7 instead of 7.5-4n4 in q8

Are these right or wrong?

also what are the domain and ranges of the final graph?
Original post by JamesExtra
Usually it's not worth a mark. If you forgot to do it, it doesn't matter


Oh thanks a lot


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Original post by H0psin
anyone else get 3/8(2x+1)^4/3 on 2? (Including +c ofc)


I think so. If you want to check, then try deriving your answer (ignoring the +c bit). If it returns to the equation in the question (which it does, so i think your answer is correct), then you're probably right!
Original post by ThatWasHard!
A couple of questions people, I'm really freaking out here. Please help.....

1) I wrote +0.5c in question 2 instead of +c
2) I wrote 4ln4 instead of ln 16 in question 2
3) i wrote 4ln4-1.7 instead of 7.5-4n4 in q8

Are these right or wrong?

also what are the domain and ranges of the final graph?


1 isn't wrong just unnecessary.
2 is wrong - 4ln4 is not the same as ln16
3 is wrong
Sorry about that :/
Original post by SH0405
Other way round; rectangle - integral.


Lol whoops was in a hurry! That's what I meant but yay


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Original post by Duskstar
1 isn't wrong just unnecessary.
2 is wrong - 4ln4 is not the same as ln16
3 is wrong
Sorry about that :/


sorry i meant 4ln4-7.5 -> this gives you the negative area?
What was the answer to the 6arcsinx-pi

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Original post by H0psin
anyone else get 3/8(2x+1)^4/3 on 2? (Including +c ofc)


Indeed, I doubled checked by differentiating it.
(sorry the LaTeΧ comes out wrong)
Unparseable latex formula:

[br]\frac {d}{dx} \left[\frac{3}{8} (2x+1)^{4/3} +c \right][br]\\[br]=2\cdot \frac{4}{3} \cdot \frac{3}{8} (2x+1)^{1/3}[br]\\[br]=(2x+1)^{1/3}[br]\\[br]Q.E.D.

Original post by Abdulmuminu
What was the answer to the 6arcsinx-pi

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0.5 or 1/2
You move pi the other side, divide by 6 then input pi divided by six into sine
Original post by Gcseboy1997
Does anyone here know if you lose a mark for leaving the area of the integral as a negative number?


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Depends on the context of the question

If a question just says "Integrate this". Then negative numbers are correct. Otherwise, If the question asks "What is the region bounded by this and this", you have to make sure that your answer is positive (it's also a good idea to include units. If none is given, then just say something like units^2. Otherwise, use the units in the question. Doubt you'll lose marks for this, but it's good practice)
I don't even know how I did in my coursework so I can't guesstimate what I got in C3. On section A question 3 For the integral I knew what to do but I was extremely stupid and put U=lnx and V=x^3 for some stupid reason. I lost 5 marks there AND 5 marks from the rates of change. So pissed at myself. I think I'm gonna get a C :/ not what I was aiming for
That was a good exam...probably 99% sure of an A* but I could've lost 1 mark. All the practising gone to waste.
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H0psin
Original post by cbartlett
I think so. If you want to check, then try deriving your answer (ignoring the +c bit). If it returns to the equation in the question (which it does, so i think your answer is correct), then you're probably right!


Just done it online and it's right! Woo
Had to come back to this one because at first glance it looked really difficult so i panicked XD

How do u think it went?
Original post by Duskstar
I think I mentioned it, I just personally wasn't sure they wanted the negative result or not. I'll try and make my post more clear when I get home today thanks.

I wrote down the negative of the exact expression for the area bounded by f(x) and y=1 and wrote that it was the area bounded by x=0, x=3, g(x) and y=0.

But I also wrote the exact expression again (but not negative) and said that it was the magnitude of the area.
WHat was the answer to the ques with rectangle area and integreals ?
How are C3 grades calculated? Is it just a straight up addition from the coursework and the paper or what?

I.e. I reckon I got 61 on the paper and I got 18 in coursework, so 79/90 would be my total RAW mark. Is this what is used to compare with grade boundaries from the website? Would this be an A from say an another year at least? I really need an A in maths to go to uni...
Was the rate of change of height of water 120π\frac{1}{20\pi} ?
Original post by Whoremaster
That was a good exam...probably 99% sure of an A* but I could've lost 1 mark. All the practising gone to waste.


What satisfaction do you get from posting that? Please inform me and the rest of us on this thread

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