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Tricky Maths Differentiation Question CCEA

Hello! I do ccea further maths, in northern ireland ...so im in year 12 here, but it's the equivalent of year 11 in England...moving on from the blabber..

I have a maths mock on this thursday and it's everything we have covered in pure maths excluding logs(we havent finished it yet). So i was doing one of the old 'Additional Mathematics papers for pure Maths(PAPER 1) of May/June 2005 by CCEA.

I came across this deadly question, can anyone help me out please? Mock on thursday.

I can't find the mark scheme anywhere on the interweb :smile: and can you tell me whereabouts i went wrong please because i only got up to the differentiation part and got dy/dx= 2ax-5, with b=-1, i don't know what a=...c=4. It's mainly just part (i) that i got stuck on, which prevented me from doing the rest of the question! Please help! I have posted this exact thread on the Maths Exams forum. http://www.thestudentroom.co.uk/attachment.php?attachmentid=481431

Thank you

RevisionLad
Original post by revisionlad
Hello! I do ccea further maths, in northern ireland ...so im in year 12 here, but it's the equivalent of year 11 in England...moving on from the blabber..

I have a maths mock on this thursday and it's everything we have covered in pure maths excluding logs(we havent finished it yet). So i was doing one of the old 'Additional Mathematics papers for pure Maths(PAPER 1) of May/June 2005 by CCEA.

I came across this deadly question, can anyone help me out please? Mock on thursday.

I can't find the mark scheme anywhere on the interweb :smile: and can you tell me whereabouts i went wrong please because i only got up to the differentiation part and got dy/dx= 2ax-5, with b=-1, i don't know what a=...c=4. It's mainly just part (i) that i got stuck on, which prevented me from doing the rest of the question! Please help! I have posted this exact thread on the Maths Exams forum. http://www.thestudentroom.co.uk/attachment.php?attachmentid=481431

Thank you

RevisionLad


You have found b correctly. I'm no sure if you've just given the answer to what c is but that is correct. For those you have used the first two bits of information given. You can use the last piece to find a.

Edit: I have just seen where this is posted. If you post in maths (not exams), you will get a better response.
(edited 8 years ago)
Original post by SeanFM
You have found b correctly. I'm no sure if you've just given the answer to what c is but that is correct. For those you have used the first two bits of information given. You can use the last piece to find a.

Edit: I have just seen where this is posted. If you post in maths (not exams), you will get a better response.


haha thankyou sean! Can you tell me how to use the last piece to find a please? You see i worked on my errors a bit and got this. IMAG0829.jpg is this correct?
Original post by revisionlad
haha thankyou sean! Can you tell me how to use the last piece to find a please? You see i worked on my errors a bit and got this. IMAG0829.jpg is this correct?


because this ends up giving me the perfect y=x^2-5x+4?? :smile:
Original post by revisionlad
haha thankyou sean! Can you tell me how to use the last piece to find a please? You see i worked on my errors a bit and got this. IMAG0829.jpg is this correct?


Your method is quite interesting, but I'm afraid that showing 1=1 doesn't show that a=1. You're overcomplicating it a bit :tongue:

The third bit of information is that the point (1,0) lies on the curve. So what can you do with that, given that you know b and c?
Original post by SeanFM
Your method is quite interesting, but I'm afraid that showing 1=1 doesn't show that a=1. You're overcomplicating it a bit :tongue:

The third bit of information is that the point (1,0) lies on the curve. So what can you do with that, given that you know b and c?


Oh yes! I was overcomplicating it! I got to the stage where it was y=a^2-5x+4 and gave up pretty much...i didnt know what to do with the (1,0) because my main aim was to find 'a'...but now i see at (1,0) y=0. hence if i subbed x=1 into my formula..then brought everything apart from the a^2...i would get 5-4=a^2...therefore a=1

Thankyou!
(edited 8 years ago)

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