Arsey's C4 Edexcel Summer 2013 Model Solutions (Both UK papers + Non-UK Paper)

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thank you arsey quick question

1) for binomial I expanded everything and then i put for each expanssion brackets and multiplied and just wrote the answer they put? did i have to show how u multiply them out?

2) dy/dx i got (-6,3) how many marks is that out of 7?

thanks

not sure about 1) it depends of what method needs to be shown.

2) this will be a really common error, I would guess at 3, but maybe 2.

Reply 41

Larry31

Woah wait what?! That is not the paper I sat this morning :O Do you reckon our school gave us the leaked C4 paper?

Reply 42

boomboom_capecod

NO. I forgot the +C on Q1. What?? :frown:

Hopefully got at least 68/75. Will that be 80 ums anyone?

Reply 43

AS01

Original post by Arsey

I would think so, prob 90 or just under.

okay thank you :smile:

Can u help me with one thing please? How can I not make stupid mistake! Well its over now but still!
I knew that its parallel to y-axis and even was like cheeky people! its gonna be undefined and was so so confident but i did 0/x rather than y/0 :frown:

Reply 44

GPODT

In the question where it says "parallel to y-axis", I equated the gradient to 1/0. I know this is undefined but then I 'flipped' both sides and got
0 = denominator . Then I proceeded to get the answer. Would the equating to 1/0 be a mistake? (Since its undefined)

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Reply 45

otrivine

Original post by Arsey

not sure about 1) it depends of what method needs to be shown.

2) this will be a really common error, I would guess at 3, but maybe 2.

I see, and the cartesian equation,

i got 4root something/-2

Reply 46

ginister

Any idea what boundary for a C and B?

Reply 47

SuziieB

Thanks Arsey!!

SOOO many people put dy/dx = 0, surely there should be some marks there?

I thought if dy/dx was parallel to the y axis, then it was equal to infinity which still made 0 overall?

Reply 48

Arsey

Original post by m4ths/maths247

I think we both might get done on the coordinates for the last questions in terms of notation!

Good effort as always :smile:

yes, indeed you could be right. I always tell my students, if you are not sure write BOTH. Need to listen to myself.

Reply 49

BobLoblawLawBlog

Me:1 Vectors:0

:cool:

Reply 50

AS01

Original post by Arsey

not sure about 1) it depends of what method needs to be shown.

2) this will be a really common error, I would guess at 3, but maybe 2.

is it??? getting (-6,3) would still give u some mark?!

Reply 51

oli_G

for 7)b) i got two possible co-ordinates (-3,6) and (-21,6) so wrote down both in my answer: how many marks lost roughly?

Rest was ok, although the vectors question took a while to get.

Reply 52

sacheeen

STUPID ERRORS GRR. Lost 3-4 marks cause of stupid mistakes in an easy paper! damn.

Thanks Arsey !

Original post by Arsey

I will attach my solutions to the this post, hopefully very shortly after this post appears.... depends if I get any errors uploading.

Roll one May/June 2014.

Hey Arsey, sorry if I'm wrong buuut for 2(b) as it asked for an approximation to root 3 should you divide by 3/5?

Reply 55

Hamburglar

Original post by Arsey

I would think so, prob 90 or just under.

Thanks so much for the solutions man :smile:

Just wondering, for 8b. I knew that the magnitude of AP was equal to AB. Then I knew that the magnitude of the scalar vector for the line equation was 3 (since it is 2,2,-1). I wanted a magnitude of 6.

Therefore, I simply took the position vector of A and did ± 2(2, 2, -1).

Basically, I did (3, -2, 6) ± 2(2, 2, -1). This gives me the same answers as yours.

When I was doing it though I thought it was a bit, weak on the mathematics and a bit more "observation". :P

Wondering if this would get all the marks?

If you say yes, I JUST GOT 75. So please say yes :smile:

Reply 56

`God

Original post by Yoyo94

I also got (-6,3) because I let dy/dx = 0!!!!!

haha me too, hope we get 2-3 marks for that.

Reply 57

Arsey

Original post by SuziieB

Thanks Arsey!!

SOOO many people put dy/dx = 0, surely there should be some marks there?

I thought if dy/dx was parallel to the y axis, then it was equal to infinity which still made 0 overall?

no, the gradient of a vertical line is undefined, similar to an asymptote.

Basically, you make the denominator equal to zero for dy/dx. However, I thought my solution might explain it a little better.

If you are not sure what is going on, draw a little diagram.

Reply 58

Caramelapps

Damn... after that C3 exam, I was so nervous this was going to be similar, that my mind went completely blank. And I have lost so many marks on silly mistakes. And I got to a point in the middle of the exam where I just thought, well there goes my £3000 scholarship. Which didn't help. Damn I worked so hard for that, just for something unbelievably stupid.