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# OCR MEI C3 Mathematics June 2016 - Official Thread watch

1. (Original post by klefki)
Attachment 554089

I got 55/12 for the area in q8, can someone tell me where I went wrong please? (sorry it's sideways)

8*3=24 not 27
2. (Original post by klefki)
Attachment 554089

I got 55/12 for the area in q8, can someone tell me where I went wrong please? (sorry it's sideways)
uno where u got 5/3 i got 14/3
3. (Original post by betapro)
No it was just 8 i got that
Yeah I've realised I was on about q5
4. (Original post by sonron202)
8*3=24 not 27
oh my god I'm an idiot ahahaha, hopefully only one or two marks for that
5. (Original post by klefki)
Attachment 554089

I got 55/12 for the area in q8, can someone tell me where I went wrong please? (sorry it's sideways)
5th equal sign, 2/3(27) = 18 not 9 and 2/3(8) = 16/3 not 8/3 as well as what was said above
6. Guys help me about question 3 with the modulus question i got x=-1/3 and -1 but i wrote just in case i need y and also put y values will i still get full marks since that is just some extra info?
7. Anyone remember what we had to integrate for question 1?
8. (Original post by ComputerMaths97)
5th equal sign, 2/3(27) = 18 not 9 and 2/3(8) = 16/3 not 8/3
I can't believe out of that entire paper the mistake I made was multiplication
9. For the proof I said because n was a positive integer smallest value of 2^n + 1 is 3, as n increases 2^n + 1 or 2^n -1 must be a multiple of 3 ( they alternate each time n increases by 1), therefore if one of the factors is a multiple of 3 the whole equation must be divisible by 3
10. (Original post by Bealzibub)
Anyone remember what we had to integrate for question 1?
1 + cos(x/2) I think
11. Guys for the height question and volume for the first one, once you get 8 did you put units? I put 8 m^2 is that right, if not will ig et marked down?
12. The proof question:

x^2n - 1 = (x^n - 1)(x^n + 1)
When x = 2
=>2^2n - 1 = (2^n - 1)(2^n + 1)

2^n only has a prime factor of 2, meaning it is not divisible by 3.

Additionally, since, for any 3 consecutive numbers, one of them must be divisible by three (since every 3rd number is a multiple of three)

We can conclude that either 2^n - 1 OR 2^n OR 2^n + 1 is divisible by 3.

Since we have proven 2^n is not divisible by 3.

Either 2^n - 1 or 2^n + 1 must be divisible by 3

Meaning (2^n - 1)(2^n + 1) = 2^2n - 1 is always divisible by 3, as required.
13. (Original post by Bealzibub)
Beautiful paper, 71/72 for me, lowest 68/72
This is what I remember:

Odd * odd = odd so divisible by 3

Area = 19/12
ak+b = k-1
4ln(4)-4
Y=(1/2)x
dr/dt = 0.05 m per minute question 3ii
P=(-4, -2)
x = ln2 question 2
x=-1 and x=-1/3
dy/dx=1/(2cos2y)
Ehy are people gettibg k-1 im dead sure its 0.5k -0.5
14. (Original post by betapro)
Guys for the height question and volume for the first one, once you get 8 did you put units? I put 8 m^2 is that right, if not will ig et marked down?
No because it was a rate without a time variable. meters cubed per meter is not meters^2, it doesn't quite work like that in real life from what I know.

But maybe.
15. For the area question I left it as 6.25 - 14/3 rather than put 19/12 will I still get all the marks?
16. (Original post by Maligaha)
Ehy are people gettibg k-1 im dead sure its 0.5k -0.5
You've subbed in the wrong value for X, it said from 1/2lnk
17. (Original post by Maligaha)
It looks like you have....
I know I didn't do that, I'd check over your maths as most people seem to have k-1 as the answer
18. (Original post by mrk1357)
11*13=143

143 is not divisible by 3

so odd*odd=odd but isnt necessarily divisible by 3
It had to be in the form 2^n-1, 2^n+1. 11 and 13 cannot be expressed in that form
19. How the hell did you do question 1? Integrating 1+cos1/2x or something.

Is 1+cosx an identity?

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20. How did you solve the y intercept for e^2x+ke^(-2x)=0?

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