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# C1 Jan 2012 Edexcel - Post exam discussion - Solutions and paper in first post

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1. (Original post by Itachi8)
Arsey you know where you had that the two equation which said it cannot intersect or something like that, but in your solution you used the discriminant but all i said was that 2x2..... cannot be factorise. How many marks do you think i lost?
Thats exactly what I did ! I made them equal each other and commented that they can 't be factorised ? im sure we did not lose all the marks.
2. (Original post by sukhys)
guys the grade boundaries you are predicting are way too low. 58/75 for an A personally
Personally I felt it was an easy paper for me as i like the graph elements. However, others hate graphs and hate the excessive manipulation of algebra. So A will be below 58.
3. (Original post by sfalcini1)
Thats exactly what I did ! I made them equal each other and commented that they can 't be factorised ? im sure we did not lose all the marks.
You would lose 1 if not 2 marks. The reason being is you had to use the discriminate of the equation to proove it doesn't factorise. This was a proof question. They had already told you they do not intersect. So you had to show full working. Therefore had to show the combined equation couldn't factorise.
4. (Original post by Mr.cool)
Personally I felt it was an easy paper for me as i like the graph elements. However, others hate graphs and hate the excessive manipulation of algebra. So A will be below 58.
i found it easy, but thats cuz i was a resit. anyway enough of c1 talk, gonna move on to c3
5. I thought this paper was really easy o_o. We did C2 straight after and that was hell, I think my brain was just frazzled after 3 hours of maths.

I think I only dropped 5-6 marks so hopefully my teacher won't eat me when she sees my C2 result ;D
6. (Original post by sukhys)
i found it easy, but thats cuz i was a resit. anyway enough of c1 talk, gonna move on to c3
I wasn't a resit but i still felt it was easy. Yh you got C3 too.
7. (Original post by Mr.cool)
I think this papers boundaries will be low. Maybe even below 70 for 100 UMS
yhh it should be low cos the cleverst girl in our centre found it really hard and she has lyk 10A* and like gets near 100% on all her test lol
8. (Original post by sfalcini1)
Thats exactly what I did ! I made them equal each other and commented that they can 't be factorised ? im sure we did not lose all the marks.
You had to put them equal to each other, and move everything to one side so you had a quadratic. You could then just say that b^2<4ac, or that the discriminant is negative.
(In the quadratic formula b2-4ac is under the square root sign, so it would be a negative number under the square root sign if 4ac is larger than b^2 - no real solutions)

Those who are saying it didn't factorise are right, but you might have had to say why.

Personally I found it fine as it was far easier than further maths, as well as the OCR additional maths fsmq that I did last year, but do think it was trickier than most of the past papers I've done. Some people I was talking to afterwards barely answered the sequences question or that last coordinate geometry one
9. (Original post by Mr.cool)
You would lose 1 if not 2 marks. The reason being is you had to use the discriminate of the equation to proove it doesn't factorise. This was a proof question. They had already told you they do not intersect. So you had to show full working. Therefore had to show the combined equation couldn't factorise.
i showed both the quadratic way and the factorsing way and said the bit about the discriment
10. (Original post by arnab)
yhh it should be low cos the cleverst girl in our centre found it really hard and she has lyk 10A* and like gets near 100% on all her test lol
Personally this paper shouldn't have been hard. Its just edexcel do not make enough exams like this so people assume c1 is going to be easy and requiring no though.
11. (Original post by arnab)
i showed both the quadratic way and the factorsing way and said the bit about the discriment
Well done.
12. (Original post by Mr.cool)
You would lose 1 if not 2 marks. The reason being is you had to use the discriminate of the equation to proove it doesn't factorise. This was a proof question. They had already told you they do not intersect. So you had to show full working. Therefore had to show the combined equation couldn't factorise.
i solved it using quadratic forumula then stated that the line do not intersect ?
13. (Original post by otrivine)
i solved it using quadratic forumula then stated that the line do not intersect ?
what reason did you give to say lines do not intesect.
14. Ummm... I did the quadratic part of it, but forgot to do the discriminant and just said that since it had no real solutions they wont intersect is that alright?
15. (Original post by Europekidda)
You had to put them equal to each other, and move everything to one side so you had a quadratic. You could then just say that b^2<4ac, or that the discriminant is negative.
(In the quadratic formula b2-4ac is under the square root sign, so it would be a negative number under the square root sign if 4ac is larger than b^2 - no real solutions)
I had the same method, I completed the square, and you got square root -7 which doesnt exist, therefore the x-coordinates and y-cordinates wont be the same.
16. looks like 100 ums will defintly be below 70.
17. b^2 < 4ac, so in the formula when you have root(b^2 - 4ac) you end up rooting a negative, so there are no real solutions.

I took a look at the paper - there were *loads* of graph / polynomial questions! But then.. there's not much else in C1 anyway
18. (Original post by Mr.cool)
what reason did you give to say lines do not intesect.
because when i applied the quadratic it was negative square root therefore maths error and i said that shows that the lines do not intersect
19. the lines did not intersect because there were no real solutions, after doing the the discriminant or quadratic equation there was a root of a minus number i think i got something around square-root of -7, not completely sure though.
20. (Original post by otrivine)
because when i applied the quadratic it was negative square root therefore maths error and i said that shows that the lines do not intersect
i guess thats an alternative method so you will get 4 marks.
Updated: May 11, 2012
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