OCR Maths C1 16/05/12 (not MEI)

Reply 20

Callumhart95

Anyone know the marks for each part of each question?

This was posted from The Student Room's iPhone/iPad App

Reply 21

samjj8

1

Someone will probably post up the past paper soon :')

Reply 22

As_Dust_Dances_

1

Original post by samjj8

4x(x-3) < 112 - So first mark

x^2-3x-28< 0 - Second mark

(x-7)(x+4) - 3rd mark/ 4th Mark

so -4 < x < 7 - which is where I stopped

Since -4 can't be negative...

its 4<x<7

How many marks would I have lost for not considering the negative value?

Have I got this question completely wrong?

I got everything right and got 4 and -7, Mr M said I should have dropped only 1 mark as you get method marks just for having it in the form a<x<b and for getting 4 and -7 but the answer is apparently 0<x<4.

Reply 23

Georgina :)

Original post by ForensicCat

oohhhh, may have lost a few marks there :0

you didn't have to use the discriminant though I don't think. If you subbed y = 2x into circle equation, and then tried to solve using the whole formula (-b +- root b^2 -4ac ) /2a, you found it gave a squared root of a negative which obviously can't be done therefore it doesn't cross and still is 'algebraicially'. Hopefully this is right anyway because that's what I did!

Reply 24

kenann

Original post by Georgina :)

you didn't have to use the discriminant though I don't think. If you subbed y = 2x into circle equation, and then tried to solve using the whole formula (-b +- root b^2 -4ac ) /2a, you found it gave a squared root of a negative which obviously can't be done therefore it doesn't cross and still is 'algebraicially'. Hopefully this is right anyway because that's what I did!

i believe that's the same as working out the discriminant, as the discriminant is just extracting what's under that sqrt sign.

i think i did well in the exam, didn't mention x can't be negative like some other people, and instead of stating what the discriminant was, i just got to a point whilst working out the discriminant (i think the furthest i simplified it was a number subtract a larger number) and then stated that the discriminant is less than zero. stupid mistake, may have dropped a mark for it too.

Reply 25

Georgina :)

Original post by kenann

i believe that's the same as working out the discriminant, as the discriminant is just extracting what's under that sqrt sign.

i think i did well in the exam, didn't mention x can't be negative like some other people, and instead of stating what the discriminant was, i just got to a point whilst working out the discriminant (i think the furthest i simplified it was a number subtract a larger number) and then stated that the discriminant is less than zero. stupid mistake, may have dropped a mark for it too.

OF COURSE IT IS! Thanks! I was getting just a bit worried because everyone else seemed to use the discriminant - i just found a longer winded way of using the discriminant - thanks!
I didn't put that x can't be negative, but that's the only thing I can find wrong. Out of five or six marks, I can't imagine putting -7<x<4 can lose any more than 2 so i'm happy. This is the second time i'm taking C1, I got 79 UMS last time, so hoping to bump it up by quite a few! Fingers crossed!

Reply 26

kenann

Original post by Georgina :)

OF COURSE IT IS! Thanks! I was getting just a bit worried because everyone else seemed to use the discriminant - i just found a longer winded way of using the discriminant - thanks!
I didn't put that x can't be negative, but that's the only thing I can find wrong. Out of five or six marks, I can't imagine putting -7<x<4 can lose any more than 2 so i'm happy. This is the second time i'm taking C1, I got 79 UMS last time, so hoping to bump it up by quite a few! Fingers crossed!

i got 76 in jan and the only mistake i made is the same as that of yours... good luck to us both :smile:

Reply 27

naturesenshi

Annoyed because I just realized I lost a mark for not realising that a length can't be negative :mad:

What was question 7?

(edited 11 years ago)

Reply 28

DJE2595

8

what did you get for question 6?
find the equation of the normal line. when x=2
the curve equation is y=(6/x^2) -5

Reply 29

computer*wiz*

i didnt do so well
i wish they would have done harder questions to distinguish between better candidates more easily! I always seem to get a few mistakes but i do so well on all the hardest questions that it never matters, now everyone will get high grades
:frown:

Reply 30

Cyclohexane

For the area problem, I got x < 4 (after showing the wrapped inequality) but stated in words than the length couldn't be negative. Would I lose a mark for not wrapping a 0 round the front?

Also, for 10iv) is showing the quadratic formula with the negative sqrt and "no solutions" correct and fully creditable? Since technically I have used the discriminant anyway...

Reply 31

naturesenshi

At q8 I thought they wanted the equation of the line that passed the circle at point P which was on the circle. So wouldn't it be that the equation of the line CP is the normal to the line?

Reply 32

barkerta

Hi...For the last question I had noooo idea how to do it but i put y=2x and the equation of the circle as simultaneous equations...
I then got a quadratic which was insolvable and so assumed that this meant that they did not meet...
would I get any marks for this? :P

Reply 33

computer*wiz*

Original post by barkerta

Hi...For the last question I had noooo idea how to do it but i put y=2x and the equation of the circle as simultaneous equations...
I then got a quadratic which was insolvable and so assumed that this meant that they did not meet...
would I get any marks for this? :P

yep thats right, I think you would have :smile:

OCR Maths C1 16/05/12 (not MEI)

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