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Edexcel A2 C4 Mathematics June 2015 - Official Thread

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Original post by kaya_lioness
Danke.I tried that But in the mark scheme they use the value of x=0.1 and placed that into the expansion.


I get it now - we cant just solve for x as x is greater than 8/9 which means the expansion would not be valid. Hence we go for x=0.1 as this means we can manipulate the expansion to get a cubed root of 7100. Sneaky Q imo

EDIT: just realised someone above has pointed this out.
Original post by Gilo98
:rofl: it is my life goal to find a flaw in your wealth of resources :wink: Just a quick check though, would it simply be

[br][br]π∫x2dydt dt[br][br][br][br]\pi\displaystyle\int x^2\frac{dy}{dt}\ dt[br][br]
Where limits are in terms of t and found using the values of y given in Q. apologies for poor formatting above, first time using LaTex

Be sure to quote me with the Q!!


This can't come up, right?
Original post by Gilo98
I get it now - we cant just solve for x as x is greater than 8/9 which means the expansion would not be valid. Hence we go for x=0.1 as this means we can manipulate the expansion to get a cubed root of 7100. Sneaky Q imo

EDIT: just realised someone above has pointed this out.


This question is very strange, in the mark scheme it says cubed root 7100 = 10 x cubed root 71, but i tried this in my calculator and they are not the same
Original post by 1 8 13 20 42
|x| < 8/9 so don't do 8 - 9x = 7100
Instead see if there's a nice clean cube factor you can take out and then multiply by at the end


Thank you :smile:
Original post by Gilo98
I get it now - we cant just solve for x as x is greater than 8/9 which means the expansion would not be valid. Hence we go for x=0.1 as this means we can manipulate the expansion to get a cubed root of 7100. Sneaky Q imo

EDIT: just realised someone above has pointed this out.


Danke :smile:
Original post by kaya_lioness
Danke :smile:


Why is it that when I put cubed root 7100 and 10 x cubed root 71 into my calculator I get different answers??
Original post by anonwinner
Why is it that when I put cubed root 7100 and 10 x cubed root 71 into my calculator I get different answers??


100 cube rooted is...

I think you're mixing it up with squared.
Original post by anonwinner
Why is it that when I put cubed root 7100 and 10 x cubed root 71 into my calculator I get different answers??


You cube root 1000 which is 10. when you are left with 10 ( cube root) 7.1 which is the same the cube root 7100 and this is equal to (cube root) 8-9x.

then you make 8-9x = 7.1
x=0.1

then you sub that into the expansion. Your answer will be ten smaller than cube root 7100 but thats it. :smile:
Original post by SeanFM
100 cube rooted is...

I think you're mixing it up with squared.


Wow I'm dumb, thanks
Original post by kaya_lioness
You cube root 1000 which is 10. when you are left with 10 ( cube root) 7.1 which is the same the cube root 7100 and this is equal to (cube root) 8-9x.

then you make 8-9x = 7.1
x=0.1

then you sub that into the expansion. Your answer will be ten smaller than cube root 7100 but thats it. :smile:


Thanks for explaining!
Original post by anonwinner
Why is it that when I put cubed root 7100 and 10 x cubed root 71 into my calculator I get different answers??


You're correct, although people are saying you're wrong. The mark scheme says 10 x cube root 71 - it is 10 cube root 7.1.. Hence you get different answers :smile: Mistake by the mark scheme really not you :biggrin:
Original post by Jimmy_M
You're correct, although people are saying you're wrong. The mark scheme says 10 x cube root 71 - it is 10 cube root 7.1.. Hence you get different answers :smile: Mistake by the mark scheme really not you :biggrin:


I knew something was wrong! Thanks
urgh ffs im ****ting myself for this exam :s-smilie:
Original post by yelllowribbon
urgh ffs im ****ting myself for this exam :s-smilie:


It's definitely the hardest A-level Maths exam, and you're not the only one. :console:

There's still a few days left so just keep at it :smile:
Original post by SeanFM
It's definitely the hardest A-level Maths exam, and you're not the only one. :console:

There's still a few days left so just keep at it :smile:


Cheers man :smile: Yeah it's just I would have liked C3 to have gone slightly better to try and take the pressure of C4, but yeah I guess just got to keep on going...
Original post by JamieF95
This can't come up, right?


Could do. Doubt they would give curve parametrically though. Thus, all you would need to do is

Unparseable latex formula:

[br][br]\pi\displaystyle\int^y_y x^2\ dy\[br][br]

Reply 1136
Avatar for Hudl
Hudl
16
how is c4 constantly 75/75 for full ums....is the date normally later than our date for c4, I feel like with the way my exams a scheduled I cant revise effectively for c4 as I have biol5 and chem5 aswell day after day. Only done like 3 papers for c4 aswell and that was before easter :frown:


EDIT:

If you want to change the limits on an integral eg you have a 1 at the top and 2 at the bottom and you have a negative inside the integral can you bring this out removing it and change the limits?
(edited 8 years ago)
Original post by TeeEm
I hope so too, for the sake of my students


Dd they not do aswell as the June 13 event?


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Original post by physicsmaths
Dd they not do aswell as the June 13 event?


Posted from TSR Mobile


in 2013 all but one got 100% (but they were a stronger cohort)

this lot have done good but not exceptional (with one exception) assuming the boundaries come roughly as I expect them
Original post by yelllowribbon
urgh ffs im ****ting myself for this exam :s-smilie:


Same, i'm literally on the toilet seat

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