Edexcel C3 June 2016 - Unofficial Mark Scheme

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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.

I think you would lose an accuracy mark.

Reply 61

yvhyhujvj

for the modulus graph i left it as 1/2ln(25/4) for x-cordinate. will i lose marks for not simplifying further?

Reply 62

Lavender26

For 8c I only got 2 positive values?

Reply 63

k.russell

can someone show their working for 9c? please reply to this/tag me so I know if you've done it !

Reply 64

Isabella~

What was q 8?
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Reply 65

toe314

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.

Got the exact same!

Reply 66

eyeman567

If I put -root5 < x < root 5

Do I get any marks at all??

Im a ****ing spac I dont know why I did that

Reply 67

mr.purplelambkin

Original post by Mattematics

4e^2x - 25 = 0
e^2x = 25/4
e^x = 5/2
x = ln(5/2)

I left it as 0.5ln(25/4). Did they want a simplified form?

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Reply 68

Further

Original post by eyeman567

What were the equations for F and G

7x-1= f(x)
g(x)= 4/(x-2)
I think

(edited 7 years ago)

Reply 69

AvocadosConstant

Original post by theereflex

For 3(c), I don't understand why the lowest value of theta wasn't just 33 from part b?

anyone help?

Same here

Reply 70

DORI

Original post by veldt127

I'm not 100% sure on all of these, but I think most are correct.

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

for q9 a i got something like 5.1...... and got the 6.7.... for part b. But i managed to prove part b, as the timings were different so different values or nah?.
Did anyone else get 5.1... or so for a??

And I swear this question has appeared before in another C3 paper....

Reply 71

icexcity_

Original post by eyeman567

If I put -root5 < x < root 5

Do I get any marks at all??

Im a ****ing spac I dont know why I did that

That's what I got :frown:

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Reply 72

eyeman567

Original post by Further

7x-1= f(x)g(x)= 4/(x-2)
I think

Yeah I think it was that, I don't get how you solve it though

I subbed G into F

Got 28 / (x-2) = x + 1

Then ended up with X^2 - x - 30 = 0

which Im pretty sure is wrong and unsolvable

Reply 73

CiaranAhern

Original post by unimaginable118

Does anyone remember how many marks the last question was? I was SO STUPID. I left it out :frown:

(( looks like someones not going to uni...

I did the same, i think it was 8 marks, thought i had done well on time as i finished question 8 as the exam finished and theres normally 8 questions but yeah 😒

Reply 74

Assfjeed

I though I got 72/75 in this paper, but when I found out that I did a silly mistake in question 3, I don't know if will get an A*.

I said a=tan^-1(2)=63.43...

And I used this value for the rest of question 3. Can I still get can A*?

Reply 75

theri mass

Original post by AvocadosConstant

Same here

3b) denominator was 2cos(theta) - sin(theta) -1,
3c) 2cos(theta)+sin(theta)-1

You need to switch sign for cos(theta+Value)=59....

to cos(theta-Value)=59....

Reply 76

Wright1998

Yeah it was definitely 4x^2+20, it looked like you could factorise and cancel out an x^2+5 but you couldn't because of the negative sign in front of the x^2 at the top