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Edexcel A2 C4 Mathematics June 2015 - Official Thread

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Original post by anonwinner
Look at part a of that question... It literally gives you it

oh right , thanks
Original post by ridirahman
As long as there isn't a really big difficult vectors question I'll be fine :smile:


I hope the differential equation is like Q2 and then vector question is Q7
lol that will make my day
Original post by 286001
Can someone help me on part iiI know that when two lines are parallel a.b=|a||b| but then I have too many unknowns image.jpg


Which paper is this?
Original post by studentwiz
:smile: do you think the paper would be harder this year?


To you question about integration by recognition its sort of like this

{ <- pretend that's an integral sign


{ [f'(x)][f(x)]^n = [f(x)^(n+1)]/(n+1)

its difficult to explain but you look for 'reverse of a differentiation'

if you differentiated a function

[f(x)]^n -> n[f'(x)][f(x)]^(n-1)

and you have to look for the reverse when integrating, thats the best i can explain it but it's not an easy concept to show in the chat :L
Original post by Maham88
oh right , thanks


No problem, always keep your eye out for things like that
Original post by 286001
Can someone help me on part iiI know that when two lines are parallel a.b=|a||b| but then I have too many unknowns image.jpg


The line that OA is a part of has the same direction vector as l2
Since OA goes through O, you can thus say OA = k(direction vector)
Then you just solve for the distance
alright **** this... lets just get this over a done with... lets just focus on C4 and try not fail too hard...
good luck everyone :smile:
Original post by frozo123
I hope the differential equation is like Q2 and then vector question is Q7
lol that will make my day


that would kill me Q7's are usually hard and I can't do any hard vectors Q's :frown:
I just hope there are no more than 8 questions unlike the c3 exam :colonhash:
Original post by Humbers
To you question about integration by recognition its sort of like this

{ <- pretend that's an integral sign


{ [f'(x)][f(x)]^n = [f(x)^(n+1)]/(n+1)

its difficult to explain but you look for 'reverse of a differentiation'

if you differentiated a function

[f(x)]^n -> n[f'(x)][f(x)]^(n-1)

and you have to look for the reverse when integrating, thats the best i can explain it but it's not an easy concept to show in the chat :L


i sort of see your point, what method do you usually use?
when we are finding the volume of a cone is the length the r value or the width the r value??
Original post by studentwiz
i sort of see your point, what method do you usually use?


you have to recognise which method you'll have to use hence the name integration by recognition
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JShell
Original post by studentwiz
when we are finding the volume of a cone is the length the r value or the width the r value??


r is the radius of the circle and h is the slanted height of the cone.
Original post by studentwiz
i sort of see your point, what method do you usually use?


If i can use recognition then i'll use that because its the fastest
I will only ever use substitution when the question tells me to
and if i cant be recognized i'll use by parts


heres an example of recognition that might make more sense

IMG_1199.jpg
Original post by 286001
Can someone help me on part iiI know that when two lines are parallel a.b=|a||b| but then I have too many unknowns image.jpg


No it's not, what have you done so far?
Can anyone give me an example of a trig integration by parts where I have to sub it back in at the end? Don't think I've come across one.
Alright, let's do this. Good luck guys, off to school.
Okay, good luck guys! Hope the paper is easy since c3 was hard af. Off to school. :biggrin:
Original post by studentwiz
when we are finding the volume of a cone is the length the r value or the width the r value??



r = radius so it will be the width of the base i guess

if you're asking because of that volume of revolution question in the recent paper (can't remember which) r = the y value

Just think about how it will look when rotated and its the radius of the cone formed
cmon! I need a high A in this
Original post by Humbers
r = radius so it will be the width of the base i guess

if you're asking because of that volume of revolution question in the recent paper (can't remember which) r = the y value

Just think about how it will look when rotated and its the radius of the cone formed


thanks for your hellp:smile:

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