OCR (Not MEI) C2 January 2013 Discussion

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Found it relatively easy in all honesty.. a few questions took some thinking about but it was all good.

I *think* i've dropped a maximum of 4 marks :biggrin:

I wish I was you xD

That was awful, was getting 97% ish in all the past papers and then the one today.... well, who knows.

Damn past papers lulling me into a false sense of security :frown:

Reply 61

stirkee

Original post by XiLE

You were negatively repped because people don't like show offs: "I *think* I dropped 4 marks."
Not because you found it hard/easy.

Urm.. How was I showing off?

The aim of this thread is to post how you found the paper, and I just posted how I found it. The think is in between '*' because I meant think as in if I got right what I'm pretty sure I got right then I will only have dropped 4.

I'm not trying to be big headed or whatever and I apologise if what I posted offended anyone, lol.

Reply 62

XiLE

Original post by stirkee

Okay okay, calm down! XD
I have nothing against you, just stated why you got negatively repped. :L

Reply 63

stirkee

Original post by XiLE

Okay okay, calm down! XD
I have nothing against you, just stated why you got negatively repped. :L

haha sorry dude, likewise!

Reply 64

lexy0202

Worst Core 2 paper I've ever seen. Hoping that the grade boundaries are really low...

Reply 65

Ranibizumab

Anyone able to find the other x value that makes a geometric progression?

It's bugging me and I still haven't worked out how to do it. :s-smilie:

Reply 66

mossss

Original post by Ranibizumab

Anyone able to find the other x value that makes a geometric progression?

It's bugging me and I still haven't worked out how to do it. :s-smilie:

log of base 2 of 256 worked for me

Reply 67

abzy1234

Original post by Ranibizumab

Anyone able to find the other x value that makes a geometric progression?

It's bugging me and I still haven't worked out how to do it. :s-smilie:

I ended up using the quadratic formula, and getting either -2 or -9 lol :s-smilie:

If a=2x, then the second term would be a * r, so 2x-7 (I think that was the second term) would be equal to 2x * r right... So r equals 2x/2x-7; then repeat for the third term, which would be a * r²... Then I went blank and diverged into something hellishly weird :tongue:

Reply 68

jenq

Original post by Ranibizumab

Anyone able to find the other x value that makes a geometric progression?

It's bugging me and I still haven't worked out how to do it. :s-smilie:

the answer is x=-2/3
didn't work that out in the exam though

Reply 69

Ranibizumab

Original post by abzy1234

I ended up using the quadratic formula, and getting either -2 or -9 lol :s-smilie:

That's what I started doing (in the last few minutes). However I had already made a mess of the paper, couldn't see my working clearly and didn't have time for a spare sheet. Also my hands were cold and I couldn't write very well. All went a bit pear shaped really.

Also, for the last question, what was the other factor of the cubic?

Reply 70

Ranibizumab

Original post by azns

You divide the the third term by he second term and make it equal to the second term divided by the first term. (Because the common ratio has to be equal). Then you solve.

arrgh! that's what I started doing before I crossed it out and tried to use a quadratic.

oh well

Reply 71

abzy1234

Original post by Ranibizumab

Oh well, unfortunately these things happen :smile:

I got something like (3x²+8x-2) I think, and solved it using the formula. Not too confident that I got the right answer though :/

Reply 72

XiLE

Original post by Ranibizumab

I got a = 1 & a = (1 +/- square root of 7)/3

I have no idea. :L

(edited 11 years ago)

Reply 73

azns

Original post by Ranibizumab

I think I got (1+rt7)/3 and (1-rt7)/3

Reply 74

Mr M

Study Forum Helper

If someone sends me a paper I will make answers for you. It was a snow day for me so I haven't seen the paper.

Reply 75

Selvey

Original post by Ranibizumab

Anyone able to find the other x value that makes a geometric progression?

It's bugging me and I still haven't worked out how to do it. :s-smilie:

Not sure if the below 'x' values are right (I can't remember them exactly), but this is the method I used.

a=2x
ar = x+4
ar²= 2x-7

Therefore, as 'ar²'÷'ar' = r, that can be set equal to 'ar'÷'a'.Therefore (2x-7)÷(x+4)=(x+4)÷(2x). From there I cross multiplied and solved; and as one of the solutions was 8, I knew the other one was correct.(If I remember correctly x was -2/3).