Turn on thread page Beta
    Offline

    2
    ReputationRep:
    (Original post by edothero)
    Yes.

    (x+1)(x+2)(x^{2}-2)< 0

    x^{4} graph that intersects the x-axis at x = -2, -\sqrt{2}, -1, \sqrt{2}

    Draw the x^{4} and find where it is < 0
    Thank god. I just saw someone talking about whole numbers for that one. Would have been dreadful if i didnt even get that.

    How many marks would you drop on the method of differences Q if you coikdnt get past doing the whole r=1,2..n stuff?
    • Thread Starter
    Offline

    15
    ReputationRep:
    (Original post by CALI1198)
    Thank god. I just saw someone talking about whole numbers for that one. Would have been dreadful if i didnt even get that.

    How many marks would you drop on the method of differences Q if you coikdnt get past doing the whole r=1,2..n stuff?
    Out of 5, maybe 3? Worst case scenario would be 4.

    Zacken might know. (Sorry for bothering you bud )
    Offline

    18
    ReputationRep:
    (Original post by Insight314)
    Told you m8. Doubting my maths skills. Now I can finally act like a proper lad and tell my friends it is a very easy paper.

    Btw, is Student's method wrong then? It was posted a few pages back but he pretty much did the same think except differentiating the ODE at the start so he can get a 2nd order ODE. This makes him get a quadratic auxiliary equation, with roots 0 and -2, whereas my method only has one root which is -2. So his complementary function would be wrong.




    Posted from TSR Mobile
    No it is not wrong because you later show the constant corresponding to it is 0...
    Offline

    15
    (Original post by Insight314)
    Posted above m8.

    How did you find it?

    I bet the mandem down at STEP prep thread finished this paper in half the time.


    Posted from TSR Mobile
    Lol, I found it quite tough. I get overly nervous during exams.

    I finished in less than an hour, but then realised I had done it all wrong, so had to do it all again.

    I might lose one or two marks, because I seem to have missed evaluating for the constant of integration for the p, q, r one. Did the p, q, r one in two ways too.
    Offline

    22
    ReputationRep:
    (Original post by CALI1198)
    Thank god. I just saw someone talking about whole numbers for that one. Would have been dreadful if i didnt even get that.

    How many marks would you drop on the method of differences Q if you coikdnt get past doing the whole r=1,2..n stuff?
    Yeah, drop 3 or 4.
    Offline

    2
    ReputationRep:
    That's cool. I was thinking 4 as I didn't even spot to split it up. Ah well, hopefully M2 and FP3 are kind if I have any chance of uni still

    Sent from my One using Tapatalk
    Offline

    15
    (Original post by Student403)
    No it is not wrong because you later show the constant corresponding to it is 0...
    prsom
    Offline

    18
    ReputationRep:
    (Original post by Insight314)
    Told you m8. Doubting my maths skills. Now I can finally act like a proper lad and tell my friends it is a very easy paper.

    Btw, is Student's method wrong then? It was posted a few pages back but he pretty much did the same think except differentiating the ODE at the start so he can get a 2nd order ODE. This makes him get a quadratic auxiliary equation, with roots 0 and -2, whereas my method only has one root which is -2. So his complementary function would be wrong.




    Posted from TSR Mobile
    No it ain't wrong cause if y satisfies the first one then it satisfies the second order thing but he found the zero part so it was all good.


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    (Original post by Student403)
    No it is not wrong because you later show the constant corresponding to it is 0...
    Yeah I thought it was equivalent but isn't your c.f. y = A + B e^{-2\theta} ?


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    (Original post by EricPiphany)
    Lol, I found it quite tough. I get overly nervous during exams.

    I finished in less than an hour, but then realised I had done it all wrong, so had to do it all again.

    I might lose one or two marks, because I seem to have missed evaluating for the constant of integration for the p, q, r one. Did the p, q, r one in two ways too.
    Yeah, I guess it was a bit too fiddly, especially at the end. You really shouldn't worry about it tbh, especially since you are such a god in STEP you would probably get in Cambridge even if you flop your other FM modules.


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    Name:  1465406748372771804745.jpg
Views: 237
Size:  353.1 KB

    4(b)?

    Unsure if the solution is missing + (c/5), or if there was additional info bar the initial FOD equation
    Offline

    2
    ReputationRep:
    (Original post by Fbiemad)
    I got the same as you. Is that correct?

    As far as I am aware; that is my worked solution
    Offline

    18
    ReputationRep:
    (Original post by Insight314)
    Yeah I thought it was equivalent but isn't your c.f. y = A + B e^{-2\theta} ?


    Posted from TSR Mobile
    CF is in the form (A + Btheta)e-2theta. It is later shown that B = 0 and A = 1/5. Also the PI is shown to be 2/5 sintheta - 1/5 costheta
    Offline

    4
    ReputationRep:
    That second order de was like y = Ax^2 + Bx - (1/12)x^-2 wasnt it.
    • Thread Starter
    Offline

    15
    ReputationRep:
    (Original post by Craig1998)
    That second order de was like y = Ax^2 + Bx - (1/12)x^-2 wasnt it.
    Correct.
    Offline

    2
    ReputationRep:
    (Original post by Student403)
    CF is in the form (A + Btheta)e-2theta. It is later shown that B = 0 and A = 1/5. Also the PI is shown to be 2/5 sintheta - 1/5 costheta
    All right. Sorry then.


    Posted from TSR Mobile
    Offline

    3
    ReputationRep:
    (Original post by Student_2357)
    To be honest, apart from Q4, they were all standard questions. There were two obvious ways to approach 4b, one was treating it as a 1st order differential and finding the integrating factor etc. and the second method was differentiating it again and treating it as a 2nd order then solve. A*-70?
    Final Q was nastier than normal and a hard Q throws people so they do worse throughout.
    Offline

    0
    ReputationRep:
    can anybody attach the model answers?
    Offline

    19
    ReputationRep:
    Anyone got the paper? I mean I doubt it, dunno why I ask, but whatever, interested to see it
    Offline

    2
    ReputationRep:
    For question 2, how many marks for 2b) worth? I didn't get a=-3 and b=9 I got b as -4 because I didn't think to use what we learned in FP1 and just subbed in 1, 2, 3... n-2, n-1 and n and noticed that you had multiple (n-2) terms so did (n/2)(n-2) for some reason. Any idea how many marks I will have lost? I got a=-3 though...
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: February 24, 2017
Poll
Favourite type of bread

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.