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AQA Core 3 - Thursday 6th June 2013 (AM) - Official Thread Watch

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    any luck>
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    What was the answer to 7c ??
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    (Original post by Lc1995)
    What was the answer to 7c ??
    Reflection in Y Axis, stretch SF 2 in X direction
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    (Original post by Hunarench95)
    Reflection in Y Axis, stretch SF 2 in X direction
    Or the other way round for that matter.
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    you don't lose marks for not putting +c do you?
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    (Original post by ThatLithuanian)
    For the Last question I did the working correct all the way to the end and got 2ln(3)-2lin(2)=ln(3/2) because for some reason i thought the 2 will cancel. How many marks will i lose for that?

    For the Mid ordinate rule i did the working out correct but i think i got 25.7 instead of 25.6 mainly because of a calculator error, and for the second part i put that its an Under estimate with a graph which doesn't really explain it at all. How many marks will i lose for that?

    And also Integrating (lnx)^2 i got x(lnx)^2-xlnx-x but i forgot about the coefficient's of xlnx and x which was 2 so how many marks do you guys think i will lose for that?
    I reckon you would lose just one mark, as you got everything else right.
    Umm, possibly you'd lose just one mark for the 25.7? If you put clear working, obvious you might lose more.
    I think the mid-ordinate rule is an under-estimate? I drew the diagram of it wrong (I guessed) but I found out the answer to the integral using my graphical calculator and it was like 25.7 something which makes the mid-ordinate rule an underestimate? So I'd say you'd get one mark for saying it's an under-estimate and then the other mark if drew the diagram properly.
    And I'm not sure how much you would lose for the lnx bit
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    (Original post by Dr_Polski)
    Or the other way round for that matter.
    yep
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    (Original post by A-New-Start)
    you don't lose marks for not putting +c do you?
    Sometimes you do, sometimes you don't. There is no way of knowing until we see the mark scheme! Most of the time you don't though
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    Only dropped like 7 marks up until the 15 mark final question

    10ai)Got the first part easily

    10aii)But then messed the integral of (lnx)^2 up

    Because I did the chain rule reckon I will get 2/4,im thinking 1/4 probably
    How many do you reckon guys?

    Finally on the last question I did the most stupid thing,still kicking myself!

    Did
    u= x^1/2
    du/dx = 1/2rootx
    2rootx du = dx

    I then subbed it in

    2rootx/(u^2 + rootx)

    But then incredibly amateurly cancelled the rootx's

    getting 1/u^2 I then integrated that and got -3/4 as the final answer-knew it seemed too simple,but the paper was so this was what confused me possibly

    I mean 7 marks for doing a trig quadratic
    That seemed to be of the same level!

    OMG 7 marks down the drain,bang and the A* is gone :\ darn I always mess up the last Q

    I solemnly swere im not gonna get the last question wrong on C4 for a silly mistake!

    Still looking at around 56/75(B I think) but considering I walked out the exam thinking I got like 70/75,not too good Hey ho,live and let learn
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    Could someone upload a photo of what they drew for the graph of: y=-f(3x) please?
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    (Original post by JTD77)
    Could someone upload a photo of what they drew for the graph of: y=-f(3x) please?
    Name:  ImageUploadedByStudent Room1370537559.820239.jpg
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    I did a similar ish drawing,was reflected in the x-axis but every x value gets 3 x as big which means every y value also gets 3 times as big

    So crossed x where y = -12 or crosses y at 6?
    Not sure though guys
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    Thanks! I did the same! Way too many graphs, hardly any written maths ;P
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    Overall, paper was really good I think. Just a tad tricky. Messed up the Cos^-1(x) part of the question.
    sketched it from -pi/2 to pi/2 instead of 1 to pi. and the Mid ordinate over estimate part, idk why but i put under estimate.
    But i think those 6 marks are the only marks i lost.
    What do you guys think the grade boundaries will be for an A*?
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    (Original post by KING2011BOB)
    I did a similar ish drawing,was reflected in the x-axis but every x value gets 3 x as big which means every y value also gets 3 times as big

    So crossed x where y = -12 or crosses y at 6?
    Not sure though guys
    f(x) intersected the y axis at (0,4) and the x axis at (6,0).

    -f(3x) is a reflection in x axis and a stretch in x-drection by factor of 1/3.

    The new intersection of the x axis should be (2,0) because of the stretch.

    The stretch should not affect the intersection of the y axis, only the reflection should.

    New intersection of y axis should be (0,-4).
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    (Original post by KING2011BOB)
    I did a similar ish drawing,was reflected in the x-axis but every x value gets 3 x as big which means every y value also gets 3 times as big

    So crossed x where y = -12 or crosses y at 6?
    Not sure though guys
    I think you have multiplied the y value by 3, where you should multiply the x value by 1/3 as you always do the reciprical when stretching in the x direction.
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    (Original post by LiquidGold)
    I reckon you would lose just one mark, as you got everything else right.
    Umm, possibly you'd lose just one mark for the 25.7? If you put clear working, obvious you might lose more.
    I think the mid-ordinate rule is an under-estimate? I drew the diagram of it wrong (I guessed) but I found out the answer to the integral using my graphical calculator and it was like 25.7 something which makes the mid-ordinate rule an underestimate? So I'd say you'd get one mark for saying it's an under-estimate and then the other mark if drew the diagram properly.
    And I'm not sure how much you would lose for the lnx bit
    Thanks I hope I don't lose to many marks, everything else apart from them three went smoothly. I just need that A*.
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    (Original post by ThatLithuanian)
    Thanks I hope I don't lose to many marks, everything else apart from them three went smoothly. I just need that A*.
    Yeh I don't think you lost too many, and there is always Core 4!
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    6) Volume of rev
    I did 1/16 pi x integral of ( 32 + (y-8)^2 )

    got 1/16 pi (32y - 2(y-8) Stupid mistake!

    Then obviously subbed in y,how many marks do you reckon I will drop I reckon probably 3?
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    (Original post by LiquidGold)
    Yeh I don't think you lost too many, and there is always Core 4!
    I'm not resitting core 4, I got the grade I desired. Its just core 3 and I cannot retake this since these are my last exams before uni. How do you think it went for you?
 
 
 
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