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# Just did AQA C2 exam watch

1. Hey,

I just did the C2 exam for AQA and was wondering what everyone thought of it.

I thought it was easy and I had enough time to check each answer 3 times and underline each answer so I was okay for time, at the end of the exam I thought I hadn't made a single mistake.

However, the question I was unsure about was the one where it asked:

Sum(from n=1 to k)Un = 0

Find k.

Un = 90 - 3n

And I used the formula for the sum of the first n terms in an AP but stupidly (though didn't know this at the time) put 90 as the first term rather than 87, which means I will get a wrong answer.

So there's a few marks lost already, I hope I will have only lost one due to followthrough marks.

So, was anything else on the paper people thought was confusing/difficult (I can't remember all the paper there was probably more I got wrong).

Also, assuming I got 74/75, is it likely this is to be considered 100 UMS?

Tom
2. I didn't think it was that bad but everyone in my college seems to have hated it! I tried to work out the sum from n=1 to k but couldn't but then looked at what the terms would be:

57, 54, 51........6, 3, 0, -3, -6........... -51, -54, -57

The negative terms cancel out the positive terms so Sn = 0 when the last term is -57

Total number of terms = 57/3 *2 +1 (+1 for the term which is 0)
= 39 (not sure, just worked it out in my head now!)

I thikn this is right.

For the rest of the paper, some of the logs parts confused me (I hate logs) and I got the differentiation question wrong (I got 22 1/4 and my graphical paper says that it is around 4) and the very last question about the 4tanxsin4x or whatever it was stumped me for ages and in the end I resorted to plotting the graph on a graphical calculator and finding the intercepts that way but I ran out of time after finding the first. But the rest was OK - should get a B at least
3. (Original post by shyopstv)
I didn't think it was that bad but everyone in my college seems to have hated it! I tried to work out the sum from n=1 to k but couldn't but then looked at what the terms would be:
Yeah, the people in my class who I spoke said it was hard.

57, 54, 51........6, 3, 0, -3, -6........... -51, -54, -57

The negative terms cancel out the positive terms so Sn = 0 when the last term is -57

Total number of terms = 57/3 *2 +1 (+1 for the term which is 0)
= 39 (not sure, just worked it out in my head now!)

I thikn this is right.
But wasn't the first term 87

I did this:
a = 90 (thinking first term was 90)
d = -3 (common difference)

(n/2)(180 + (n-1)*(-3)) = 0
(n/2)(183 - 3n) = 0
(183n - 3n^2)/2 = 0
n(183-3n)/2 = 0
n(183-3n) = 0
183 - 3n = 0
3n = 183
n = 61, damn, why did I put 60?

But I think the correct answer was:
(n/2)(174 + (n-1)*(-3)) = 0
174 - 3n + 3 = 0
177 - 3n = 0
3n = 177
n = 59

For the rest of the paper, some of the logs parts confused me (I hate logs)
Yeah, logs are difficult sometimes, especially if you misread the question and solve the wrong question, I realised though and did them correctly (I hope).

and I got the differentiation question wrong (I got 22 1/4 and my graphical paper says that it is around 4) and the very last question about the 4tanxsin4x or whatever it was stumped me for ages and in the end I resorted to plotting the graph on a graphical calculator and finding the intercepts that way but I ran out of time after finding the first. But the rest was OK - should get a B at least
The differentiation, who knows whether or not I got that right.

Yeah the last question was pretty difficult at first sight, btw it was 4tan4xsin4x

I said:
0 <= x <= 90
0 <= 4x <= 360
Let 4x = Theta
0 <= Theta <= 360

Then I solved it for theta (well it had already been solved in a previous question)

cos Theta = 0.25
Theta = arccos .25 and (360 - arccos .25)
Therefore:
4x = arccos .25 and (360 - arccos .25)
x = (arccos .25)/4 and (360 - arccos .25)/4

What did everyone get for the normal to the curve C, I think I got y = -x/8 + 1/x
4. Did it say normal? Damn I worked out the tangent should still get marks for finding the gradient at intercept I guess. Oh and I meant intergration when I said differentiation - I keep geting the two mixed up.
5. One question asked for the tangent and on a different question it asked for the normal.

The tangent one was the one where you had to work out the area of the triangle OAB on the axes.

The normal was in the question with y = x^0.5
6. C1 was absolutely pee pee easy but C2 was awful.
Q8 was only question im sure i got full marks on!!
i had to go over the paper so many times, eventually got it done but it was nasty and everyone at my college found it really hard. still, picked up some easy marks and should have done well enough to get an A with C1 and D1 being so easy.
7. Ye i got 59 for the sum to k terms, after a few checks lol.

For the normal to the curve the gradient i got was -1/8 but it didnt ask for the equation.

Can anyone remember any more questions/answers...?
8. I got -1/8 for the normal too.

57, 54, 51........6, 3, 0, -3, -6........... -51, -54, -57

The negative terms cancel out the positive terms so Sn = 0 when the last term is -57
That was exactly my thought process, assuming you meant 87, 84, 81......-81, -84, -87. All the maths seemed to work at the time, but I'll see. I really hate progressions - they never make any sense to me.
9. (Original post by xXxKatiexXx)
Ye i got 59 for the sum to k terms, after a few checks lol.

For the normal to the curve the gradient i got was -1/8 but it didnt ask for the equation.

Can anyone remember any more questions/answers...?
The questino only asked for the gradient?!?!?
Are u sure, i thought it read find the equation of the normal...
All in all i thought the c2 paper was pretty straight forward. Got 59 for k.
10. Oooo i dunno, could have asked for the equation, pretty sure it only said the gradient tho, anyone remember? It asked for the equation of the tangent at some point, but i thought it only asked for the gradient on the normal question...?
11. I hope they don't mark me down for giving the whole equation.

One of my biggest problems is not reading the question fully, I just read a little bit, assume it's asking what I'm used to (from revision) and answer incorrectly.
12. (Original post by TomX)
I hope they don't mark me down for giving the whole equation.

One of my biggest problems is not reading the question fully, I just read a little bit, assume it's asking what I'm used to (from revision) and answer incorrectly.
LOL

Anyone here doin aqa s1 tomorrow?
13. (Original post by damaster275)
LOL

Anyone here doin aqa s1 tomorrow?
Yeh i am. Hopefully, it shouldn't be as bad as C2 so i'll be able to push my UMS up a bit considering i'll probably get a D or an E in c2! Good luck to everyone else taking s1, im sure u'll all be fine!
14. So wot was the answer to quetion 5)c) in C2, i did the whole paper easy enogh but that log question i could not do anybody got any explanations?
15. also in c1 the area of the curve i got was 11.5 was it right
16. (Original post by Feelin' dizzy)
So wot was the answer to quetion 5)c) in C2, i did the whole paper easy enogh but that log question i could not do anybody got any explanations?
Which one was that? 12.5? 3 + Log (54 + 24Sqrt(7))?
17. (Original post by Feelin' dizzy)
also in c1 the area of the curve i got was 11.5 was it right
I got -11/12 I think
18. (Original post by TomX)
Which one was that? 12.5? 3 + Log (54 + 24Sqrt(7))?
Question 5c i) write Un and U2n in terms of n
ii) hence prove logUn - logU2n= nlog(4/3)
iii)log(u100/u200) prove that this equals 12.5 to 3sf

i cud not do one of those questions, help!

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