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Edexcel C3 June 2016 - Unofficial Mark Scheme Watch

1. (Original post by Irmakozturk)
Im pretty sure the p in 5ii was 1?
Does anyone remember the question?
no. it was differentiating x = sin^2(2theta) which gives 4sinthetacostheta which gives 2sin(4theta) inverting that to find dy/dx gives 0.5cosec(4theta)
2. what was question 5
3. (Original post by Ibraldo)
Here is the proof, each step represents a possible mark.
got a rogue 2 in the first line there
4. For question 2b. I got that x>(plus or minus)sqrt5. So x is greater than -root5 and also greater than root5, so writing x>-root5 would be wrong? as only x>root5 is required
5. Does anyone have any idea what 63 marks might be?

Plus the question where you had to find the equation of the line, did anyone get the gradient of the the tangent -4, therefore the gradient of the normal was 1/4?

Thanks
6. (Original post by chandlerr)
For question 2b. I got that x>(plus or minus)sqrt5. So x is greater than -root5 and also greater than root5, so writing x>-root5 would be wrong? as only x>root5 is required
the answer is x < -sqroot5 and x> sqroot5, both inequalities will likely be needed for full marks, the trick was drawing the x^2 - 5 as a graph and solvingby looking at the inequlity c2 style
7. Is there a list of how many marks for each question

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8. (Original post by leestitt)
Does anyone have any idea what 63 marks might be?

Plus the question where you had to find the equation of the line, did anyone get the gradient of the the tangent -4, therefore the gradient of the normal was 1/4?

Thanks
I got a gradient of the tangent as 10, so the gradient of the normal was -1/10, I think I got y-16=-1/10(x-3) and then simplified, I don't think you need to simplify it though as it didn't say in the question so leaving it in that form would be fine I guess
9. Does anybody know how many marks each question was worth? Thanks
10. Does anyone have the number of marks that go with each part of each question?
11. (Original post by chandlerr)
I got a gradient of the tangent as 10, so the gradient of the normal was -1/10, I think I got y-16=-1/10(x-3) and then simplified, I don't think you need to simplify it though as it didn't say in the question so leaving it in that form would be fine I guess
No if I remember the gradient was 2 when you put x=3 into dy/dx. Then it was asking for the normal so m = -1/2.

2y-32 = -1 (x-3)
2y-32=-x+3
x+2y-35 = 0 for the full 5 marks.
12. (Original post by chandlerr)
I got a gradient of the tangent as 10, so the gradient of the normal was -1/10, I think I got y-16=-1/10(x-3) and then simplified, I don't think you need to simplify it though as it didn't say in the question so leaving it in that form would be fine I guess
I got 12 as the gradient so -1/12 as the gradient for the normal.. There are so many range of answers for the gradient that I'm just scared now
13. ok guys so i have a question about how many marks i'd get for question 6, where you had to find the values of A and B and then the eqn of the normal.

I tried part a properly a few times and could not get it for some reason, but then i looked at part b. i noticed if you differentiated the given function then you'd get rid of A. I put the original eqn into my calculator to find the gradient of the tangent at the point (2), then obviously found the normal gradient and equation.
Through this i could create and equation for B, so work out that B=4. then just sub this into the original eqn to find A=3. i just wrote 'comparing coefficients gives...' for the 'working' (though I didn't cross anything out, but i'm pretty sure it was all wrong anyway)

obviously this is a very dodgy method, how many marks am I looking at? thanks.
14. What. In question 6 , I got 33.5 instead of 17.5. I think my equation was y-16=-0.5(x-3). God damn it, every single paper Edexcel has made this year is hard/just not a simple standard one. Rip my A*. I got alpha as -26.56 etc so I ended up getting different values for all the other parts of question 3. And then the identities question I ended up with cos^2x/sin^2x everytime and I think i also messed up the part B of it by ignoring the 4x somehow.
15. Hopefully you don't lose a mark for leaving it as 1/2ln(25/4)
16. Any one remember the boundaries for question 8 as pi/4<X<pi/2 or something like that
17. Is there a list of how many marks for each question

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18. (Original post by Patrick Gekko)
ok guys so i have a question about how many marks i'd get for question 6, where you had to find the values of A and B and then the eqn of the normal.

I tried part a properly a few times and could not get it for some reason, but then i looked at part b. i noticed if you differentiated the given function then you'd get rid of A. I put the original eqn into my calculator to find the gradient of the tangent at the point (2), then obviously found the normal gradient and equation.
Through this i could create and equation for B, so work out that B=4. then just sub this into the original eqn to find A=3. i just wrote 'comparing coefficients gives...' for the 'working' (though I didn't cross anything out, but i'm pretty sure it was all wrong anyway)

obviously this is a very dodgy method, how many marks am I looking at? thanks.
If I remember the question, to find A and B you had to do long division to find out the remainder which let you find A and then you could find the B so you had the simplified function. Then differeentiate that, sub in the x=3 into original function to get the y value which was 16. Put x=3 into dy/dx which came as 2, then you're finding the normal so m=-1/2. Then work out the equation like normal.
19. (Original post by jshep000)
If I remember the question, to find A and B you had to do long division to find out the remainder which let you find A and then you could find the B so you had the simplified function. Then differeentiate that, sub in the x=3 into original function to get the y value which was 16. Put x=3 into dy/dx which came as 2, then you're finding the normal so m=-1/2. Then work out the equation like normal.
yeah i know how to do it, but i didn't do such a method.. if i got the right answers but used a not very mathematical method, how many marks do you think i'd get?
20. I got A=-5 for the last question. Did I do something wrong or is there a typo?

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