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Edexcel A2 C3 Mathematics 12th June 2015

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Original post by Medicjug
Hey can you explain the last part I'm really really confused


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The bit about choosing between plus or minus 2a?
Original post by 1asdfghjkl1
so proof by contradiction is in the specification but theres never been any questions on it? what could they ask us to prove?


WTF it's not in the specification!!!
Original post by Raj_B961
quick question, how do we find the maximum or minimum value in trig questions?????????????????????????????????????????????????????????????????????????????????????????????????????????


set cos/sin/tan or whatever to equal to -1, 0, 1 depending on the question

for example (2cosx)/3, the maximum value will be where cosx = 1 and so the maximum value is 2/3
Original post by JizzaStanger
The bit about choosing between plus or minus 2a?


The last part after you find k=2a ImageUploadedByStudent Room1434058892.777358.jpg


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Original post by Moniii16081997
Need help on part b.
Thanks ImageUploadedByStudent Room1434057895.915545.jpg


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Tricky, but if you find dy/dx, then find the gradient of the normal using -1/(dy/dx), then use that it goes through the origin to find the equation of the normal, and finally substitute q=x... it gets you that.
Original post by frozo123
I liked A and C, made loads of mistakes on B hopefully 78/80though
cba for Unit 5gonna get like a C on it lol


lol yeah a and c were ok messed up on b , was relying on unit 4 but ....need to do good in unit 5 now
okay I know this is a stupid question and prob the easiest question ever but I feel like I'm loosing my mind can someone answer to this please?

so if you have a question like; (6x(x-1)^1/2)^2
wouldn't you get 36x^2(x-1)^5/2 ??

but it says the answer is 36x^2(x-1)

what happened to adding the powers when multiplying them??
(edited 8 years ago)
Capture.JPG
Original post by NikolaT
WTF it's not in the specification!!!


it is???
Original post by ridirahman
okay I know this is a stupid question and prob the easiest question ever but I feel like I'm loosing my mind can someone answer to this please?

so if you have a question like; (6x(x-1)^1/2)^2
wouldn't you get 36x^2(x-1)^5/2 ??

but it says the answer is 36x^2(x-1)

what happened to adding the powers when multiplying them??


1/2 plus 1/2 is 1, not 5/2
Have you guys got any tips for when were stuck on a question?
Like maybe a process we can go through to help get on track?
Original post by ridirahman
okay I know this is a stupid question and prob the easiest question ever but I feel like I'm loosing my mind can someone answer to this please?

so if you have a question like; (6x(x-1)^1/2)^2
wouldn't you get 36x^2(x-1)^5/2 ??

but it says the answer is 36x^2(x-1)

what happened to adding the powers when multiplying them??


(a)^2 * (a)^3 = a^5. (you add here)

(a^2)^3 = a^6 (you multilpy a^2 by a^2 by a^2 giving a^6), so here you multiply.
(edited 8 years ago)
Original post by ridirahman
okay I know this is a stupid question and prob the easiest question ever but I feel like I'm loosing my mind can someone answer to this please?

so if you have a question like; (6x(x-1)^1/2)^2
wouldn't you get 36x^2(x-1)^5/2 ??

but it says the answer is 36x^2(x-1)

what happened to adding the powers when multiplying them??


Easy mistake, the powers are separated by brackets so they're multiplied rather than being added.
Original post by 1asdfghjkl1
Capture.JPG

it is???


Holy ****. Well I'm ****ed if either of those proofs come up.
Original post by Medicjug
The last part after you find k=2a ImageUploadedByStudent Room1434058892.777358.jpg


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What paper is that?
Original post by ridirahman
okay I know this is a stupid question and prob the easiest question ever but I feel like I'm loosing my mind can someone answer to this please?

so if you have a question like; (6x(x-1)^1/2)^2
wouldn't you get 36x^2(x-1)^5/2 ??

but it says the answer is 36x^2(x-1)

what happened to adding the powers when multiplying them??

a^n X a^m =a^m+n
(a^n)^m= a^mn
Original post by JizzaStanger
The bit about choosing between plus or minus 2a?


For the last part I keep getting two solutions when they only want one :frown:


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Original post by lordoftheties
Have you guys got any tips for when were stuck on a question?
Like maybe a process we can go through to help get on track?


Look over the previous parts of the question, as they might be leading you to something, even if it doesn't say hence.
Original post by NikolaT
Holy ****. Well I'm ****ed if either of those proofs come up.


:frown:(((
Original post by lordoftheties
Have you guys got any tips for when were stuck on a question?
Like maybe a process we can go through to help get on track?


Think about what you know about the topic.

Check if it's a multiple part question, check if there are any links between the parts.

Check if there is anything in the formula booklet..

Check the time. If you've spent too long and haven't got anywhere, do a different question and come back.

Also drink some water between questions.
Original post by NikolaT
Holy ****. Well I'm ****ed if either of those proofs come up.


Disproof by counter example is easy, you just find a value for which the statement doesn't work, someone said that edexcel took contradiction of the spec but never updated the website

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