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    (Original post by Insight314)
    All right, gonna make sure not to upload before that. If I have time I am also planning on going through the solutions with one of the maths teachers in my school (super good at maths, PhD and everything) so that would be cool.
    Ah, alright. You'll have a bank of solutions up on TSR by the end of the second day for further checking/worrying.
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    STEP II, 2013 Q3 part ii, to deduce b>0, I used the fact that the smaller root of the turning points >0 so -a-sqroot(a^2-b)>0, so
    -sqroot(a^2-b)>a, then squaring and cancelling gives b>0, I don't know if this is right.

    and to deduce a<0, I used the same argument as above, as -sqroot(a^2-b)>a, a must be negative.

    and c<0, I just said that this can be deduced from the graph (in order to have 3 positive roots).

    I don't know if all this is correct or not (The answer from TSR forum is done in a different way).
    Could someone check if this is correct?
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    (Original post by Geraer100)
    ...
    year?
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    (Original post by Vesniep)
    year?
    Sorry forget to add that
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    (Original post by Geraer100)
    Sorry forget to add that
    Sorry mate haven't done the paper yet .
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    (Original post by Vesniep)
    Sorry mate haven't done the paper yet .
    Yeah no problem, thanks any way!
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    (Original post by Geraer100)
    STEP II, 2013 Q3 part ii, to deduce b>0, I used the fact that the smaller root of the turning points >0 so -a-sqroot(a^2-b)>0, so
    -sqroot(a^2-b)>a, then squaring and cancelling gives b>0, I don't know if this is right.

    and to deduce a<0, I used the same argument as above, as -sqroot(a^2-b)>a, a must be negative.

    and c<0, I just said that this can be deduced from the graph (in order to have 3 positive roots).

    I don't know if all this is correct or not (The answer from TSR forum is done in a different way).
    Would you mind spoilering this? Haven't done this paper yet


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    Step iii, 2014

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    Not that bad, on the whole, but not the peak of the papers I've done. Haven't marked it properly yet, so these are just estimates.

    Q1. Took me a while to get on course with this, as I was messing about with trying to homogenise all the equations in a, b and c, but once I worked out the easiest method it wasn't too bad. 19/20.

    Q2. Very quick, essentially a repeat on that question off 2005 or something. Not even that bad algebraically to be honest. 20/20.

    Q5. This was my sixth question. First few bits fell out with relative ease, but my algebra went askew and so I couldn't complete one of the directions of implication in (ii). Taking into account a slightly dodgy appreciation of the logic throughout, probably about 14/20.

    Q9. My first question. Again, first few parts were fine, and little more than shunting algebra about. The inequality with the tangents took me a while though. 18/20.

    Q10. Very pretty question and conclusion. 20/20.

    Q11. Not tremendously tough, algebra was a bit annoying for the tensions but otherwise it was perfectly reasonable. 19/20.

    Comes to about 110 in the end, but it badly illustrates my over reliance on nice mechanics.



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    (Original post by drandy76)
    Would you mind spoilering this? Haven't done this paper yet


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    Done! And sorry about that, didn't notice that before
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    (Original post by Zacken)
    Ah, alright. You'll have a bank of solutions up on TSR by the end of the second day for further checking/worrying.
    Cool.

    On a side note, I am practicing STEP complex numbers/vectors questions right now, and I am kind of stuck on understanding one thing. I am currently doing III 2014 Question 5 and for ABCD being a square, none of the solutions I've looked at (TSR, mark scheme, official hints and solutions, examiner's report) explain why the iff condition is the one that needs to be shown. The only hint I got was from the mark scheme which says that \arg(b-a) +\frac{\pi}{2} = c-b but do not explain further that. What am I missing? It is possible that it is something simple and basic so don't judge me, I almost never did any complex number questions before this week.


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    (Original post by Insight314)
    Cool.

    On a side note, I am practicing STEP complex numbers/vectors questions right now, and I am kind of stuck on understanding one thing. I am currently doing III 2014 Question 5 and for ABCD being a square, none of the solutions I've looked at (TSR, mark scheme, official hints and solutions, examiner's report) explain why the iff condition is the one that needs to be shown. The only hint I got was from the mark scheme which says that \arg(b-a) +\frac{\pi}{2} = c-b but do not explain further that. What am I missing? It is possible that it is something simple and basic so don't judge me, I almost never did any complex number questions before this week.


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    Sorry, I haven't done III 2014 just yet!
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    (Original post by Insight314)
    Cool.

    On a side note, I am practicing STEP complex numbers/vectors questions right now, and I am kind of stuck on understanding one thing. I am currently doing III 2014 Question 5 and for ABCD being a square, none of the solutions I've looked at (TSR, mark scheme, official hints and solutions, examiner's report) explain why the iff condition is the one that needs to be shown. The only hint I got was from the mark scheme which says that \arg(b-a) +\frac{\pi}{2} = c-b but do not explain further that. What am I missing? It is possible that it is something simple and basic so don't judge me, I almost never did any complex number questions before this week.


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    Do you know that multiplying by e^iθ represents a rotation of theta degrees anti-clockwise?


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    (Original post by Krollo)
    Do you know that multiplying by e^iθ represents a rotation of theta degrees anti-clockwise?


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    Yeah. This is for last part of the question as far as I can recall.


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    (Original post by Zacken)
    Sorry, I haven't done III 2015 just yet!
    It's 2014 though!


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    (Original post by Insight314)
    It's 2014 though!


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    Whoops, I meant 2014.
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    Can I quote the arctan addition formulae or do I have to prove them?

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    For 1 2014 question 2(iii) why do they lose the modulus signs on the first line of working in the mark scheme?


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    (Original post by fa991)
    Can I quote the arctan addition formulae or do I have to prove them?

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    quoting shud be ok tbh. it is one line prof anyway just say "let A=arctan n B= leads to A+B=...
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    (Original post by Glavien)
    For 1 2014 question 2(iii) why do they lose the modulus signs on the first line of working in the mark scheme?


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    think about |x|=x or -x dependng if x>=0 or x<0.
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    (Original post by fa991)
    Can I quote the arctan addition formulae or do I have to prove them?

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    I'd add in the extra line of proof. It shouldn't take longer than 10 seconds extra than just quoting it.
 
 
 
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