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# STEP III 2012 Discussion Thread Tweet

Maths exam discussion - share revision tips in preparation for GCSE, A Level and other maths exams and discuss how they went afterwards.

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1. Re: STEP III 2012 Discussion Thread
(Original post by Farhan.Hanif93)
4 fulls, two meagre partials. Somewhere between 75 and 90, I'd imagine (barring any serious mistakes)
Well done, i'm sure you'll have met your cambridge offer then
2. Re: STEP III 2012 Discussion Thread
(Original post by Rahul.S)
yh I like those type of questions.....like q8 in II and q8 in III.

I remember trying to do prove via induction initially for the Fibonacci- but almost instantly decided a direct proof was called for. how was AEA btw? My bredwin was saying it was hard....harder than II!!!
I went for induction for Fibonacci, seemed to work, unless I made a big mistake somewhere

AEA was easy! I think I got around 85/100 and that was because I had not done any vectors since C4. It was nothing compared to STEP
3. Re: STEP III 2012 Discussion Thread
how many marks do you guys think I will get for doing the whole of question 7 except part (iii)?
4. I've looked though the paper (although being on the bus means I can't do solutions ) and I would say this is a standard paper. It disadvantages people who like integration, but it has 2 DEs which can be done. I think boundaries will be similar to last years or less (maybe 59 for a 1)

I will do questions after jitsu training, but nice questions I think are 2 and 7, with 4, 5 and 6 being do-able. (5 looks nasty, but I have a feeling it will be quite nice to work with)

But for now, well done everyone as you have completed STEP!

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5. Re: STEP III 2012 Discussion Thread
(Original post by maksokio)
It may be that I am being stupid here for some reason but I think that if z=y^n(dy/dx)^2 then dz/dx=ny^(n-1)(dy/dx)^2+2y^n(dy/dx)(d^2y/dx^2) when the formula reads dz/dx=ny^(n-1)(dy/dx)^3+2y^n(dy/dx)(d^2y/dx^2)
Your calculation is wrong, d/dx y^n = ny^(n-1)(dy/dx), so after multiplying by the (dy/dx)^2 bit you find the first term should have a (dy/dx)^3 factor (and so matches the exam paper).
6. Re: STEP III 2012 Discussion Thread
(Original post by DFranklin)
Your calculation is wrong, d/dx y^n = ny^(n-1)(dy/dx), so after multiplying by the (dy/dx)^2 bit you find the first term should have a (dy/dx)^3 factor (and so matches the exam paper).
indeed I was being stupid there, calculated (y^n)'=ny^(n-1) instead of ny^(n-1)dy/dx
7. Re: STEP III 2012 Discussion Thread
I think it was a nice paper! I liked the first question, but it was idiotically presented; somebody has to be sent off.
Is anyone bothered posting solutions? I could do some tonight only if they are needed.
8. Re: STEP III 2012 Discussion Thread
Can anyone upload the paper, pretty please Just come back from hospital and I need to relax :P

Edit: Ahh, I see where it is .
9. Re: STEP III 2012 Discussion Thread
Felt awful walking out of the exam, I normally like STEP III papers, but I'm good at calculus and the big trig questions, which there was none of :/.

I just want to stop thinking about this paper now, so can someone let me know how they think I did so I can have a bit of closure.

I only did 5 questions :/.

1 - Used n=1 and n=-2 on each part. And I built a relationship between z and y using the result they gave at the top. But I couldn't solve the equation I got for z in x, for either case. So barely any real progress.

3 - Drew all graphs, got up to the final show that equation, and couldn't do that, didn't state relevance to initial graphs.

5 - Completed.

7 - Up to the final summation, think my result for Z2(t) was wrong (looked a little too elaborate)

8 - Completed, but unsure of my result for the part about there being 2 values. I just found the second value and stated conditions on n, without any real proof or complete method.

Last edited by LucasJ94; 28-06-2012 at 19:24.
10. Re: STEP III 2012 Discussion Thread
(Original post by DFranklin)
...
Any opinions on the difficulty of the paper?
11. Re: STEP III 2012 Discussion Thread
I didn't manage to finish any of the questions fully so didn't do very well, but saying that, I thought it was a nice paper, it was a lot more accessible than older papers and I did a lot more than I thought I'd manage.
12. Re: STEP III 2012 Discussion Thread
(Original post by fruktas)
I agree, but the thing is that without this info we couldnt do the question! I ended up saying let z = x^2/4 (without any explanation) in order to show the result given in Q1
You could have integrated the RHS wrt x to find an expression for z. Don't be put off put my the cubic term, just integrate this by parts.
13. Re: STEP III 2012 Discussion Thread
(Original post by Euclid)
You could have integrated the RHS wrt x to find an expression for z. Don't be put off put my the cubic term, just integrate this by parts.
I did, I managed to obtain an expression for z in terms of y, and I could not see how to proceed further
14. Having thought about it, I'd say this was a paper where my lack of applied prep was a problem as I just didn't understand 1 and 3 &6 were in areas of significant weakness for me

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15. Re: STEP III 2012 Discussion Thread
(Original post by fruktas)
I went for induction for Fibonacci, seemed to work, unless I made a big mistake somewhere

AEA was easy! I think I got around 85/100 and that was because I had not done any vectors since C4. It was nothing compared to STEP
induction ofc could work....I decided to do a direct proof instead. They didnt mention a specific method so its fine.

your AEA should be S standard

oh yh how did your bredwin do?
16. This shall be my only visit and my only post on this thread but:

I THINK I got 2 full solutions, 2 15+ and 1 that I'd call a 5-8 (complex numbers with p one - I did the whole first part and a bit of the next equation).

I also did a 'full solution' for q1 but I will probably get no marks for it. I basically spotted without any sort of justification (was more working back from the answer in my head) that z = ¼x² and then worked out the answer from there. Not even sure if it was right but I got to the right answer and did the same thing for the second part (got something * e^something )
17. Re: STEP III 2012 Discussion Thread
Done question 1 completely, (also got e^something for the second part :P)
oh and I don't think any information was missing! Although the phrasing of the question was certainly awkward...

Couldn't do the simplifing in Q2 but deduced the two equations. didn't do part ii)

Managed to show the first equation in 4.

Done 6 completely (not sure if graphs correct though).

Did 7 except part iii).

Done 8 completely.

Is that enough for a 1? what do you think?
18. Re: STEP III 2012 Discussion Thread
(Original post by hassi94)

I also did a 'full solution' for q1 but I will probably get no marks for it. I basically spotted without any sort of justification (was more working back from the answer in my head) that z = ¼x² and then worked out the answer from there. Not even sure if it was right but I got to the right answer and did the same thing for the second part (got something * e^something )
did you see my solution - post 46 in this thread - i'm not sure what you're saying fits with my thinking
19. Re: STEP III 2012 Discussion Thread
(Original post by fruktas)
I agree, but the thing is that without this info we couldnt do the question! I ended up saying let z = x^2/4 (without any explanation) in order to show the result given in Q1
I had to come back to say I did exact this Though I feel I dud well enough even if I get 0 on that one
20. Re: STEP III 2012 Discussion Thread
I think this is how I did part i) of question 1)
Does that seem right?
Attached Files
21. STEPIII2012Q1i).pdf (92.6 KB, 111 views)
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