C3 (Not MEI) - Thursday June 14 2012, AM

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  1. Doctor.'s Avatar
    • Vengeful, Imperial Overlord of The Student Room
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    C3 (Not MEI) - Thursday June 14 2012, AM
    Didn't see the thread around so thought I might ad well get this started!

    How is everyones revising going? What are you revising with? What books have you used? Tips? -just anything C3 OCR related really

    I have covered the content to a reasonable extent and done.the mock exam. Didn't do amazing or anything but did okay

    Tomorrow I will go through the C3 book and just try all questions for each of the topics.
  2. Doctor.'s Avatar
    • Vengeful, Imperial Overlord of The Student Room
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    Erghhh, just going through the text book questions there are waaaay too many
    differentiation/integration questions!!! Exponentials messed with my head, then I realised what I was doing
  3. Contrad!ction.'s Avatar
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Doctor.)
    Erghhh, just going through the text book questions there are waaaay too many
    differentiation/integration questions!!! Exponentials messed with my head, then I realised what I was doing
    Although I'm not taking this exam in summer (did it in Jan) I'm happy to supply worked answers/help on tricky questions from the OCR book or past papers. I've still got my books/papers lying around somewhere so I can take photos and annotate answers if you'd like me to.
  4. Doctor.'s Avatar
    • Vengeful, Imperial Overlord of The Student Room
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Contrad!ction.)
    Although I'm not taking this exam in summer (did it in Jan) I'm happy to supply worked answers/help on tricky questions from the OCR book or past papers. I've still got my books/papers lying around somewhere so I can take photos and annotate answers if you'd like me to.
    That would be awesome, there isn't many I messed up on (thankfully), I will get them up tomorrow

    Thanks again!
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Doctor.)
    That would be awesome, there isn't many I messed up on (thankfully), I will get them up tomorrow

    Thanks again!
    I probably won't be posting pictures until late afternoon tomorrow (school has a filter system) but I could always type stuff out and LaTeX stuff up.

    I find the formula book's generally useful, in C3 and 4 especially. For cos 2x and sin 2x, you don't have to remember anything as you can just let A and B = x and use the formula for cos(A+B) or sin(A+B). The integration/differentiation section's also pretty useful as it saves you spending ages deriving results they already give. Also, the quotient rule's in there.
  6. Doctor.'s Avatar
    • Vengeful, Imperial Overlord of The Student Room
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Contrad!ction.)
    x
    Decided to do C3 tomorrow noww! So hopefully will put up the questions I cant do then

    Thanks again, really do appreciate the help if I do manage to pull off an A/A* in maths I am giving you guys £100 each and a: :jumphug:!!




    (minus the £100 I'm broke! :ninja: )
  7. Contrad!ction.'s Avatar
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Doctor.)
    Decided to do C3 tomorrow noww! So hopefully will put up the questions I cant do then

    Thanks again, really do appreciate the help if I do manage to pull off an A/A* in maths I am giving you guys £100 each and a: :jumphug:!!




    (minus the £100 I'm broke! :ninja: )
    I've got pretty much all the exam questions answered properly, so I should be good to help you. I won't have worked solutions for Jan's exam, but I answered them all when I sat the exam so I should be able to get those done too. What areas in particular are your weakest? Might see if I can find some resources or some decent tricks for different types of question.


    This is my C3 section of the wall, ignore how it says C4. Those things are pretty handy to remember - although some of it can be derived using the formula booklet, it can make it easier to spot things and means you can work through things quickly.

    I might have to hold you to that

    ...dammit.
  8. Doctor.'s Avatar
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Contrad!ction.)
    x
    :ahee: I have come to the conclusion that you have wooden flooring in the room/corridor next to your room :holmes: oh and your notes are pretty awesome!

    C3...It's weird,in the Jan '12 mock I checked with Mr M's answers and I dont 'think' I got anything wrong. Maybe if I upload my exam sheet and the paper you could just have a quick look and see If I went wrong anywhere?
    (don't want you spendibg hours making a worked answers sheet just for me )

    I don't think I struggle much...LOL Transformstions :facepalm: Almost as bad as when i integrate instead of differentiate

    I will go through the misc questions tomorrow and post up my incorrections oh and the C3 mock

    lol i bet i made 100s of mistakes in the mock but just pretend they dont exist. I do that a lot :lol:
    Last edited by Doctor.; 30-04-2012 at 23:26.
  9. Contrad!ction.'s Avatar
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Doctor.)
    :ahee: I have come to the conclusion that you have wooden flooring in the room/corridor next to your room :holmes: oh and your notes are pretty awesome!

    C3...It's weird,in the Jan '12 mock I checked with Mr M's answers and I dont 'think' I got anything wrong. Maybe if I upload my exam sheet and the paper you could just have a quick look and see If I went wrong anywhere?
    (don't want you spendibg hours making a worked answers sheet just for me )

    I don't think I struggle much...LOL Transformstions :facepalm: Almost as bad as when i integrate instead of differentiate

    I will go through the misc questions tomorrow and post up my incorrections oh and the C3 mock

    lol i bet i made 100s of mistakes in the mock but just pretend they dont exist. I do that a lot :lol:
    Nope, a crappy carpet.

    Do it - I'll need to see the paper, but I should be able to see any issues. I hope your handwriting isn't as bad as mine.

    I'd make revision cards with the transformations on them - so one side says 'y=f(x-a)' and the other says 'translation, a units, positive x direction', for example. I am, actually. I'm taking C1 again in June and helping a friend with her retake as well.

    Yeah, do that It'll be interesting to see how much I can remember :laugh:

    '+k? Yeah, I know that should be there. Benefit of doubt mark'll do'... oops.

    ...actually, I don't have any of: Jan 09, Jun 09, Jan 10, Jun 10, Jan 11, so if you need help with those I'll need to see the question too.
  10. Doctor.'s Avatar
    • Vengeful, Imperial Overlord of The Student Room
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Contrad!ction.)
    Nope, a crappy carpet.

    Do it - I'll need to see the paper, but I should be able to see any issues. I hope your handwriting isn't as bad as mine.

    I'd make revision cards with the transformations on them - so one side says 'y=f(x-a)' and the other says 'translation, a units, positive x direction', for example. I am, actually. I'm taking C1 again in June and helping a friend with her retake as well.

    Yeah, do that It'll be interesting to see how much I can remember :laugh:

    '+k? Yeah, I know that should be there. Benefit of doubt mark'll do'... oops.

    ...actually, I don't have any of: Jan 09, Jun 09, Jan 10, Jun 10, Jan 11, so if you need help with those I'll need to see the question too.
    http://s1262.photobucket.com/albums/ii604/Hayley_Cassells/ My question paper for C3
  11. Doctor.'s Avatar
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    The questions I cannot do: (so far, lol there's bound to be more :cry:)

    They're attached and thank you
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    Last edited by Doctor.; 01-05-2012 at 12:34.
  12. Contrad!ction.'s Avatar
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Doctor.)
    The questions I cannot do: (so far, lol there's bound to be more :cry:)

    They're attached and thank you
    For 3)b):
    From a, \sec^2 x - \tan^2 x=1

    Generally, if part of a question gets you to 'state' or 'show that', one of the next parts will use it. That is the case here.

    \sec^2 x - \tan^2 x=1 can be expressed as the difference of two squares. See if this helps you.

    For 7:
    \int e^x \ dx = e^x + C
    \int e^-^x \ dx = -e^-^x + C
    Generally,
    \int e^f^(^x^) \ dx = \frac{1}{f'(x)} e^f^(^x^) + C
    Bung the limits in, rearrange and it should come out right. Might need a bit of manipulation, and if you get stuck, just quote me back in.

    Will post with next couple in a min.
    Last edited by Contrad!ction.; 01-05-2012 at 19:04.
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    2):

    Rate of decay: 12% per hour. After each hour, there is 0.88% left from the hour before. So the proportion = 0.88^r. See if you can finish this one off.

    5's asterixed, so it's not on the syllabus. I could have a go, but it's waffly. For the first part, you'd plot the values and chuck on a line of best fit. Should show exponential growth. To find a, find where the line crosses the y axis - t will = 0, so y=a. Then you can use another point to find b. b) will use your a and b values from a).
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    13) When you complete the square, you can easily see the range of a graph's equation. The stuff outside the bracket is the range, so once you've completed the square, you'll have something outside the bracket which should equal -7.

    8 a and b, plus the extra bit) You'll have to work backwards. Undo everything. So reflect it back in the x direction, unstretch, and then move it in the opposite direction.

    2b) - is that two b or not two b? from a, translation, 3 units, positive y direction and translation, 1 unit, positive x direction.
    Again, it needs undoing. Try to apply the same idea from 8).
    Last edited by Contrad!ction.; 01-05-2012 at 17:09.
  15. Doctor.'s Avatar
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Contrad!ction.)
    For 3)b):
    From a, \sec^2 x - \tan^2 x=1

    Generally, if part of a question gets you to 'state' or 'show that', one of the next parts will use it. That is the case here.

    \sec^2 x + \tan^2 x=1 can be expressed as the difference of two squares. See if this helps you.

    For 7:
    \int e^x \ dx = e^x + C
    \int e^-^x \ dx = -e^-^x + C
    Generally,
    \int e^f^(^x^) \ dx = \frac{1}{f'(x)} e^f^(^x^) + C
    Bung the limits in, rearrange and it should come out right. Might need a bit of manipulation, and if you get stuck, just quote me back in.

    Will post with next couple in a min.
    3b: isn't it, \sec^2 x - \tan^2 x=1 which can be the diff of two squares?
    (\sec x - \tan x) (\sec x - \tan x)=1?
    Confused on this one sorry

    I get the integral part of 7, I think its the re-arrangement!

    Not too sure how I would get the integral (e^x + e^-x) to the corrct one
    Last edited by Doctor.; 01-05-2012 at 18:04.
  16. Doctor.'s Avatar
    • Vengeful, Imperial Overlord of The Student Room
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Contrad!ction.)
    2):

    Rate of decay: 12% per hour. After each hour, there is 0.88% left from the hour before. So the proportion = 0.88^r. See if you can finish this one off.

    5's asterixed, so it's not on the syllabus. I could have a go, but it's waffly. For the first part, you'd plot the values and chuck on a line of best fit. Should show exponential growth. To find a, find where the line crosses the y axis - t will = 0, so y=a. Then you can use another point to find b. b) will use your a and b values from a).
    Got the first one now lol, it wasnt that bad :facepalm: thank you

    No chance am I going to do that one...I always thought the asterisk meant it is just really hard :lol:
  17. Doctor.'s Avatar
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Contrad!ction.)
    13) When you complete the square, you can easily see the range of a graph's equation. The stuff outside the bracket is the range, so once you've completed the square, you'll have something outside the bracket which should equal -7.

    8 a and b, plus the extra bit) You'll have to work backwards. Undo everything. So reflect it back in the x direction, unstretch, and then move it in the opposite direction.

    2b) - is that two b or not two b? from a, translation, 3 units, positive y direction and translation, 1 unit, positive x direction.
    Again, it needs undoing. Try to apply the same idea from 8).
    13: I forgot about the outside being equal to the range, got It now

    8: I still dont understand how to exactly get started. Just complete the square and start from there?

    2b:I got it! I guess 8 is comp sq then

    Thank you!

    only a few more chapter to go now
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Doctor.)
    3b: isn't it, \sec^2 x - \tan^2 x=1 which can be the diff of two squares?
    (\sec x - \tan x) (\sec x - \tan x)=1?
    Confused on this one sorry

    I get the integral part of 7, I think its the re-arrangement!

    Not too sure how I would get the integral (e^x + e^-x) to the corrct one
    Ah *******s, yeah it is. I noticed the first one and corrected it, didn't realise that I'd still left one in. I copied the LaTeX for the sin2 identity and didn't change the signs.

    Difference of two squares: a2-b2=(a+b)(a-b). That better?

    Show me what you get when you put the limits in.
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Doctor.)
    13: I forgot about the outside being equal to the range, got It now

    8: I still dont understand how to exactly get started. Just complete the square and start from there?

    2b:I got it! I guess 8 is comp sq then

    Thank you!

    only a few more chapter to go now
    8's the same as 2, unless I'm looking at a different question to you.

    Say a person wants to give you a present. They'll put it in a box, apply wrapping paper and then tie a bow on it. You'll take the bow off (undo step 3), remove the wrapping paper (step 2) and then take it out of the box (1). It's the same principle as algebra, really.

    What they do:
    Translate 2 units, negative x direction
    Stretch, y direction, factor 4
    Reflect in y axis

    What you have to do:
    Reflect back in y axis
    Undo the stretch: stretch, y direction, factor 1/4
    Undo -2 units x translation: +2 units, x direction

    So the first transformation takes 12x^2-48x+20 to 12(-x)^2-48(-x)+20=12x^2+48x+20

    That better?
  20. Doctor.'s Avatar
    • Vengeful, Imperial Overlord of The Student Room
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    Re: C3 (Not MEI) - Thursday June 14 2012, AM
    (Original post by Contrad!ction.)
    8's the same as 2, unless I'm looking at a different question to you.

    Say a person wants to give you a present. They'll put it in a box, apply wrapping paper and then tie a bow on it. You'll take the bow off (undo step 3), remove the wrapping paper (step 2) and then take it out of the box (1). It's the same principle as algebra, really.

    What they do:
    Translate 2 units, negative x direction
    Stretch, y direction, factor 4
    Reflect in y axis

    What you have to do:
    Reflect back in y axis
    Undo the stretch: stretch, y direction, factor 1/4
    Undo -2 units x translation: +2 units, x direction

    So the first transformation takes 12x^2-48x+20 to 12(-x)^2-48(-x)+20=12x^2+48x+20

    That better?
    I understand just retried both of the questions and understood what I am doing Thanks!
    (Original post by Contrad!ction.)
    Ah *******s, yeah it is. I noticed the first one and corrected it, didn't realise that I'd still left one in. I copied the LaTeX for the sin2 identity and didn't change the signs.

    Difference of two squares: a2-b2=(a+b)(a-b). That better?

    Show me what you get when you put the limits in.
    Woo got it Your method worked fine, just needed a tiny bit of substituting

    Start with:\sec^2 x - \tan^2 x=1

    Split it into the Diff of squares: ( \sec x - \tan x ) ( \sec x + \tan x )x=1

    Then you can see the one form (a) will sub into ( \sec x + \tan x ) and we can get to the answer
    Last part was simple rearranging it, not too bad. Just depended on getting the first part correct
    Thanks so much for that one, it's been bugging me for a ages :lol:


    The 'e' question:

    \int e^x  - e^-^x  \dx = e^x + e^-^x Is this correct? Now I sub in the values of 0 & 1.

     e + e^-^1 - 2 ?? I don't understand where I am going wrong
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