OCR MEI C3 Maths June 2015

Reply 460

Primus2x

2

Original post by RemainSilent

WHat was the answer to the ques with rectangle area and integreals ?

Integrate f(x) between 1 and 4.

The area of the rectangle is 3, subtract the integral you use worked out from that.

Reply 461

cbartlett

2

Original post by AlexParmenter

I assumed r=h because it was iscosceles

I did the same.

I'm pretty sure that the isoceles right-angled triangle is a typical one to remember at A-level. They'll more than likely accept it as is.

Otherwise. Proof is simple. Just a case of using GCSE trig to prove that r=h

Reply 462

Whoremaster

7

Original post by georgiariane

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

Your tears of sorrow <3

Reply 463

RemainSilent

3

Original post by Primus2x

Integrate f(x) between 1 and 4.

The area of the rectangle is 3, subtract the integral you use worked out from that.

I deffo got soemthing like 3ln3-4 and put a modulus sign between it? (i got decimal value of -0.7041..) but cant remeber doing anything with rectangles :s-smilie:

Reply 464

Primus2x

2

Did any of you get tracing paper to plot the inverse of f(x) when it is restricted to x>ln(2)

I used my compass bisected angle the x axis and y axis made with each other in quadrant where both x and y are positive to draw y=x with my pen as accurately as I could. I marked out where f(x) meets y=x because that is the same point where the inverse of f(x) meets f(x)

I used my ruler to measure the coordinates of the minimum point of f(x) (ln2, -1) and plotted (-1, ln2) on the graph, I did the rest by eye.

Reply 465

cbartlett

2

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) No. C is an unknown constant. If you were to use this later on, C would correct itself. +c looks nicer than +0.5c, but either is accepted
2) 4ln4 = ln4^4 = ln256. Sorry, you would lose the marks here
3) Sorry. This again is incorrect

If i were you, don't worry about it! Seriously. If you've went through and shown your method, then you'll maybe lose an answer mark or two, but the overall affect won't be an instant fail!

If you are worried though. Use this as motivation to revise C4. Try to nail that C4 exam!

Reply 466

Gcseboy1997

2

Original post by cbartlett

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)

Do you remember the context for this paper? Thanks!

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Reply 467

Alex621

17

Original post by Primus2x

Did any of you get tracing paper to plot the inverse of f(x) when it is restricted to x>ln(2)

I used my compass bisected angle the x axis and y axis made with each other in quadrant where both x and y are positive to draw y=x with my pen as accurately as I could. I marked out where f(x) meets y=x because that is the same point where the inverse of f(x) meets f(x)

I used my ruler to measure the coordinates of the minimum point of f(x) (ln2, -1) and plotted (-1, ln2) on the graph, I did the rest by eye.

I plotted a point at (3,3) as 3 was marked on both axis then I drew y=x and did the rest by eye. I think I marked the point (-1,ln2) and labelled the y axis intersection

They normally don't have to be too accurate anyway do they?

Reply 468

krippleman1

Is there error carried forward in a2 math? For example I messed up the integration by parts question, got u and dv/dx the wrong way around. All 5 marks gone?

Grade boundaries for that c3 paper?

Reply 469

Gcseboy1997

2

Original post by AlexParmenter

I plotted a point at (3,3) as 3 was marked on both axis then I drew y=x and did the rest by eye. I think I marked the point (-1,ln2) and labelled the y axis intersection

They normally don't have to be too accurate anyway do they?

General shape (1 mark)
Y intersection (1 mark)

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Reply 470

Hody421

15

How much is a 100 UMS for C4?

I think I need near that to get an A*...

Reply 471

Primus2x

2

Original post by GREIMER

here are some of my answers:

1. (1.107,4.094)
2. (3/8)(2x-1)^(4/3)
3. 4ln2 - 15/16
4. 1/20pi
5. remind me what this question was please
6. i) 0.5
ii) (sqrt2)/2
7.remind me what this question was please
8. cant remember exactly what the questions were but for shaded area i got 4-3ln3 i think
9. i) Q (-2, -8)
ii) ln(3) lol not sure if these two questions were in 8 or 9
iii) what was this question?
iv) g(x) = ln(sqrt(x+1) + 2) domain x>/=-1 range y>/=ln2

1. I wrote [latex](\arctan{2}, e^{2\arctan{2}} \cdot \frac{\sqrt{5}}{5})[\latex] down as exact coordinates and wrote "this is approximately (1.107,4.094)"
2. Got that with a +c I hope you remembered to do that too, I also doubled checked by differentiating back.
3. I think I got that
4. Yes, that was the answer I was least sure of. Now I see everyone else got that, I am confident I will get full marks.
5. Haven't the slightest clue, sorry.
6.i) Yes
ii) Yes, good thing I remembered the rationalize the denominator
7. I think this was the one where

f(x)=\frac{1-x}{1+x}

and you had the find the stationary points and inverse function. I think the second part was to show that g(x) was an even function.
8. i) Got that
ii) whether it was , 8 or 9 I think I got them eight

Wait was the even function question thing in 9?

(edited 8 years ago)

Reply 472

Connorbwfc

5

For arcsin(x)=arcos(x)

Would you get any marks for just putting the answer as Root(2) / 2 ?????

Reply 473

Connorbwfc

5

Does the coursework count for 10% of Core3 or 20% or Core 3?

Reply 474

RemainSilent

3

Original post by Connorbwfc

For arcsin(x)=arcos(x)

Would you get any marks for just putting the answer as Root(2) / 2 ?????

i know many people who did hat just wrote answers (inc me) depends on the examiner sometimes they can give u 1/2 marks but if MEI want to discriminate between the best and better candidates they might not accept it; we will lose deffo 1 mark as it asked show something not state

Reply 475

Connorbwfc

5

Original post by RemainSilent

i know many people who did hat just wrote answers (inc me) depends on the examiner sometimes they can give u 1/2 marks but if MEI want to discriminate between the best and better candidates they might not accept it; we will lose deffo 1 mark as it asked show something not state