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# OCR (not MEI) C2 - Wednesday 20th May 2015 watch

1. Q8(i)
https://68baf9f6baae001b7abe18b6e880...20C2%20OCR.pdf
Im stuck .Will this part involve logs ?
2. (Original post by giantbecky)
the answers are 3 and 1/2 and actually I just tried 1/2 and I don't think that works as -7x1/2 +3 = -1/2 and you can't take logs of negative numbers...

So maybe the textbook is wrong?
Yeah the textbook is wrong, and the correct answers are:
(−7±√73)/4
3. (Original post by Sahil_)
Yeah the textbook is wrong, and the correct answers are:
(−7±√73)/4
okay thankyou!!
Q8(i)
https://68baf9f6baae001b7abe18b6e880...20C2%20OCR.pdf
Im stuck .Will this part involve logs ?
Yep. 2=1.25^x

log1.25(2)=x
therefore x=3.11

*uses a^b=c is the same as loga(c)=b
5. (Original post by Issy :))
Yep. 2=1.25^x

log1.25(2)=x
therefore x=3.11

*uses a^b=c is the same as loga(c)=b
Im confused on the mark scheme for part ii of the question.They used 1.25^0 but I only used from 1.25^1 to 1.25^4.Why am I wrong ?
6. Checking in
How's everybody doing?
7. Because the limits are 0 and 4 because it is bound by the y-axis where x=0
therefore 1.25^0 not 1.25^1 . Hope this helps

Im confused on the mark scheme for part ii of the question.They used 1.25^0 but I only used from 1.25^1 to 1.25^4.Why am I wrong ?
8. (Original post by Issy :))
Because the limits are 0 and 4 because it is bound by the y-axis where x=0
therefore 1.25^0 not 1.25^1 . Hope this helps
Ok,part (iii),I said it was an underestimate because it looks like its under the curve,but the mark scheme says its an overestimate.Like wtf ?
Ok,part (iii),I said it was an underestimate because it looks like its under the curve,but the mark scheme says its an overestimate.Like wtf ?
The tops of the trapezia are above the curve- see pic below
10. (Original post by Issy :))
The tops of the trapezia are above the curve- see pic below
Thank you so much !I just realsied when I make the trapezia,the line will go above the curve.Ty.
11. (Original post by Issy :))
The tops of the trapezia are above the curve- see pic below
Sorry again,but Im stuck on q9 part i.
I have twwo factors with an unkown remainder, and having the a there throws me off.
12. F(2)= F(-2)
therefore (imput this value for x)...
4a+2b+2= 4a-2b-14
4b=16
b=4
then work out a. Basically the a cancels but you need to be brave and work through the calc that looks too complicated to do. Sneaky exam board.
Sorry again,but Im stuck on q9 part i.
I have twwo factors with an unkown remainder, and having the a there throws me off.
13. (Original post by Issy :))
F(2)= F(-2)
therefore (imput this value for x)...
4a+2b+2= 4a-2b-14
4b=16
b=4
then work out a. Basically the a cancels but you need to be brave and work through the calc that looks too complicated to do. Sneaky exam board.
Ty once again !
https://68baf9f6baae001b7abe18b6e880...20C2%20OCR.pdf
From question 8(ii) to 9v0,Im stuck.Can you guide me please ?
Ty once again !
https://68baf9f6baae001b7abe18b6e880...20C2%20OCR.pdf
From question 8(ii) to 9v0,Im stuck.Can you guide me please ?
8ii) 2^x - 3
2^0 - 3
1 - 3 = -2

8iii) 0 = log2^x - 3
3 = log2^x
x = log(base2)3

I think of it as 2 to the power of x = 3 and the power always goes to the right. The thing that is getting 'the power' is the base.

iv) y = 2^p - 3 (p,62)
62 = 2^p - 3
65 = 2^p
log65 = log2^p
log65 = plog2
p = log65/log2

Trapezium rule is easy.
Ty once again !
https://68baf9f6baae001b7abe18b6e880...20C2%20OCR.pdf
From question 8(ii) to 9v0,Im stuck.Can you guide me please ?
16. Quick question, during the trapezium rule, is it the odd numbers multiplied by 2 ?
Ty once again !
https://68baf9f6baae001b7abe18b6e880...20C2%20OCR.pdf
From question 8(ii) to 9v0,Im stuck.Can you guide me please ?
Quick question, during the trapezium rule, is it the odd numbers multiplied by 2 ?
No it's all except the first and last the formula is on the data sheet
19. (Original post by giantbecky)
No it's all except the first and last the formula is on the data sheet
Just realised that I'm thinking about core 3' thanks
20. (Original post by Issy :))

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I'm confused.For the trapezium rule,I thought it would be this set up,
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