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# Edexcel C3 June 2016 - Unofficial Mark Scheme

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1. What was the thing you had to differentiate in Q2??
2. (Original post by Narxs)
I did 4e^2x =25
e^2x=25/4
2x=ln(25/4)
x=0.5ln(25/4)

But didn't simplify ant further would this be alright??
You might lose 1 mark, I think it said it wanted answers in their simplest form. It is equivalent though.
3. I got 1/2ln(6.25) which is the same as ln(2.5)
4. Does anyone know mark by mark what each question was worth?
5. What is the answer of question 1A, mine is 1/6
6. Does anyone know what the functions were for question 1 since I somehow got it wrong.
7. (Original post by sierra117)
I believe you're wrong. It was -4x^2 + 20, not -20. Therefore the answer stated by this post is correct.
Hmm I think i did something stupid in the exam saying that -4x^2+20 = -4(x^2+5) which is wrong. Would I get the final mark for writing the -4x^2+20/(x^2+5)^2 ? Because I definitely wrote that.
8. totally correct. i even remember checking them on my calculator
9. How many marks q6 was
I got 1/2ln(6.25) which is the same as ln(2.5)
It asked for simplest form; you could root that (as it's half a log) and get ln2.5.
11. Can someone tell me the equations for question 1

I cant ****ing believe I couldn't solve it.

You put G into F then you equate it to X?

why was I getting a unsolvable quadratic equation

**** my life
12. (Original post by eyeman567)
Can someone tell me the equations for question 1

I cant ****ing believe I couldn't solve it.

You put G into F then you equate it to X?

why was I getting a unsolvable quadratic equation

**** my life
fg(x) = x
g(x) = f^-1(x)

Find the inverse of then equate and solve.
13. (Original post by Mattematics)
fg(x) = x
g(x) = f^-1(x)

Find the inverse of then equate and solve.
What were the equations for F and G
14. (Original post by eyeman567)
What were the equations for F and G
I can't remember, sorry.
15. (Original post by eyeman567)
What were the equations for F and G
I would like to know this. Am sure I have got 72/75 except if I didn't get question 1 correct - which I cant remember if i got 5 and -6
16. (Original post by veldt127)
I'm not 100% sure on all of these, but I think most are correct.

1.
A -5, 6
B 6

2.
A (20-4x^2)/(x^2+5)^2 Might not be simplest form
B >sqrt(5), <-sqrt(5)

3.
A R= sqrt(5)
a= 26.57°
B 33.0°, 273.9°
C 86.1°

4.
Ai 21
ii ln(2.5)
iii 25
B Show that question
C 1.4368, 1.4373
D Show the root was in [1.4365, 1.4375]

5.
i 0.9463
ii 0.5cosec(4Y)

6.
A A=3, B=4
B Normal eqn. -0.5x + 17.5

7.
A graph of arcsin, sort of a rotated S shape. Went through (0,0), (-1,-pi/2), (1,pi/2)
B -1-0.5sqrt(3)

8.
A Trig proof
B -2.848, -1.277, 0.294, 1.865

9.
A 6.740 - dose after 4 hours
B show that dose equalled a value after 7 hours
C 5ln(2 + 2e^-1)
A = 5, B = 2

Sorry about the formatting, I'll try to improve it once I'm home.
do you have the mark allocations?
17. F********K.

Omg for 3.a. I got r=root(5) , and I got a=63.43...

I got the value of 'a' wrong and I used this value for the rest of my question!!!!!
How many marks would I lose if I got the method correct?
18. (Original post by Dieselblue)
For 5i what did people do with the sin and cos?

Also part 2a is wrong, -4x^2-20=-4(x^2+5) so -4/x^2+5
nope it was 20-4x^2. not -20-4x^2. there was no further cancellation
19. Agree with all
20. Working for 8a and 7
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