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# Edexcel A2 C4 Mathematics June 2015 - Official Thread watch

1. Partial fractions:
If the fraction is top heavy by one degree, e.g has x^3 on top and x^2 on bottom, then it can be expressed in the form Ax + B + C/denominators - is this correct?
2. (Original post by AffirmedCube)
Any good links where I can quickly go over and learn everything I need to know about vectors including:
- How to prove intersection
- When it is parallel/perpendicular
- Reflection in the line
- Everything else

Really hope vectors isn't a large feature of tomorrow's paper. I am struggling with dat shiz!
(Original post by ASDuh97)
^Second this
(Original post by TheRaspberry)
Thirded
the cheat sheet, solomon worksheets and notes on here might help
http://www.physicsandmathstutor.com/...-level-core-4/
3. (Original post by Bustamove)
tbh, that C3 exam wasn't that hard... I don't know what came over me in the exam... maybe it was lack of sleep or something, but after comparing my answers with Arseys.. I made some ridiculous stupid mistakes... I know the grade boundaries for an A will be somewhere between June 13 -14... I don't think it will fall that much from june 2014 tbh... Arsey predicts 57 ums for an A.. I pray that his prediction is correct...
i think it caught people off guard because of the wording/style of the questions :/ me too, i wanted just a good solid B in this, but lack of sleep and stress turned me into a headless chicken in that exam, ended up realising what i needed to do for most questions when the time was already up which is a shame
4. (Original post by ember8)
so if it was say cos3xsinx, or sin3xsinx, what would the formula look like? as in, is it always sina +sinb?
basically you have to look at the right hand side of the sum and product identities and see which ones are similar to one you are integrating
so for sin3xsinx it is similar to cosA- cosB =-2sin((A+B)/2) sin((A-B)/2)
for cos3xsinx it is similar to sinA- sinB =2cos((A+B)/2) sin((A-B)/2)
and then you integrate . hope that makes sense
5. (Original post by Bustamove)
Nice! don't you mean June 2014? I don't think theres a Jan 2014...
Naa, if tomorrows papers anything like the June 2014 paper I can kiss good bye to an a* i done a jan 2014 international C4 paper from edexcel
6. (Original post by kdevitto)
Does anyone have a guide or a way of thinking on how to tackle differential equations? When I've started them I'm fine I just find it hard to know where to start? Thanks
there is a diffferentials section on this pdf that might help?
7. (Original post by Bustamove)
tbh, that C3 exam wasn't that hard... I don't know what came over me in the exam... maybe it was lack of sleep or something, but after comparing my answers with Arseys.. I made some ridiculous stupid mistakes... I know the grade boundaries for an A will be somewhere between June 13 -14... I don't think it will fall that much from june 2014 tbh... Arsey predicts 57 ums for an A.. I pray that his prediction is correct...
I need A*AA for my econ offer too, but no, it wasn't hard, it was just harder than normal. I still found it quite simple.
8. (Original post by Maham88)
basically you have to look at the right hand side of the sum and product identities and see which ones are similar to one you are integrating
so for sin3xsinx it is similar to cosA- cosB =-2sin((A+B)/2) sin((A-B)/2)
for cos3xsinx it is similar to sinA- sinB =2cos((A+B)/2) sin((A-B)/2)
and then you integrate . hope that makes sense
you're a star!
9. (Original post by jubilant_joej)
Partial fractions:
If the fraction is top heavy by one degree, e.g has x^3 on top and x^2 on bottom, then it can be expressed in the form Ax + B + C/denominators - is this correct?
yeah, and if it is the same e.g. x^2 on top and x^2 on the bottom it can be done as A + B/denominators
10. (Original post by H0PEL3SS)
I need A*AA for my econ offer too, but no, it wasn't hard, it was just harder than normal. I still found it quite simple.
11. How do you find percentage error?
12. (Original post by ember8)
you're a star!
haha thanks
13. Guys what shapes volume equations do we need to know and area.

cone?
14. I agree so much

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15. (Original post by joe1545)
How do you find percentage error?
error / true value * 100
16. (Original post by ember8)
i think it caught people off guard because of the wording/style of the questions :/ me too, i wanted just a good solid B in this, but lack of sleep and stress turned me into a headless chicken in that exam, ended up realising what i needed to do for most questions when the time was already up which is a shame
I made some massive stupid mistakes which made me head bang the table once I realised what I did....
e.g.
Question 9.. I forgot that K was a negative constant.. so wrote decreasing.. even though it was highlighted in BOLD.... like wtf.. how can I not see it? 2 marks gone...

question 2... I forgot the label the point where the graph intersects the x axis...
I worked it out, but I forgot to put it on... I also forgot to put the asymptote for the second graph.. (I just wrote y=5 at the bottom but I didn't label it.. Worked it out, forgot to draw it in the diagram..)
Thats 3 of the easiest marks lost from that 6 marker diagram question...

this continues throughout my paper.. I don't know what the **** was wrong with me in that exam hall.... all those mistakes had led me to getting borderline A if Arsey's prediction is correct...

I'm gonna make sure I get a good sleep tonight... What I did in C3 may have costed me my A* and my uni offer...This is deffo not going to happen tomorrow.. I will make sure of it...
17. (Original post by joe1545)
How do you find percentage error?
i think its (exact - approx/estimate )/exact *100
18. https://a086a5a2f39bda93734c56a63fab...%20Edexcel.pdf

How do you do Q7? fml
19. (Original post by Freddy-Francis)
error / true value * 100
So say if the exact area under the curve is 10, and the approximated value is 9,

then the percentage error = (10-9)/10 * 100 = 10%
20. Integrate

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