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Edexcel A2 C3 Mathematics 12th June 2015

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I know the answer what I dont get is when we do modulus equations and we draw the graph and for example in this case the negative part of one graph the |x| - a graph crosses the postitive part of the other graph 3x + 5a

What I would normally do in this case is to put a negative in front of the equation underlining the negative part ie

-(x - a) = 3x + 5a
---> -x + a = 3x + 5a

The markscheme says its just -x - a = 3x + 5a etc I dont know why

Dude the modulus function is only on the x hence the x becomes negative and the a is not effected. Read the question :biggrin:

Reply 1601

TheAnnabelle

Original post by Gome44

I think it's been taken out the spec, Edexcel just haven't updated it (from what I hear)

Thanks I was freaking out about it!

Reply 1602

Ripper Phoenix

guys on the june 14R paper how is no. 4 part iii done? :smile:

I keep getting an extra (x+1) on the cos theita

Reply 1603

princessedeparis

Original post by Frank Costello

Can someone explain what happens to the graph is transformed by the function f(|x|)

Basically you draw the graph like normal but only for x>=0
and then you reflect in the y axis

Reply 1604

User1686961

Original post by Maham88

can anyone help me on question 13 b) jan 2015 why does the cos(30t+16.7) have to equal to -1 when it is asking for the max value ?
https://drive.google.com/folderview?id=0B1ZiqBksUHNYak5FZDJHS1ZSTHM#list

Max of H so the negative value needs to become a positive for that to happen it must equal to -1. ( minus*minus=Plus).

Reply 1605

Hudl

Original post by ThatGuyRik

Dude the modulus function is only on the x hence the x becomes negative and the a is not effected. Read the question :biggrin:

Legend, thanks

Reply 1606

studentwiz

Original post by Myuna

thats so neat and clear, do you do that in the exam?

Reply 1607

TheRaspberry

Original post by Ripper Phoenix

yes that is correct

Original post by MrVisneski

It is 3^x squared times e^x cubed not plus.

Original post by SeanFM

It looks like you've used the product rule there. If it's (e^x)^3, then by the chain rule that would be 3(e^x)^2 * e^x, or 3(e^x)^3. That's differentiating the function of the function and multiplying by the differential of the thing inside the brackets.

It's tiny, but not 0. if e^-x = 0, then ln(-x) = ln(0) = math error, so I guess e^-x can't be 0.

Thanks everyone!

Reply 1608

Nirm

Can anyone tell me if this is correct or not?
So say the angle is 30 degrees and you found that out using arcsin.
And if question asked to find values from -180<x<180
(Using the CAST/Quadrant method)
Would the solutions/values be : 30,150,-30,-150?

Reply 1609

Ripper Phoenix

Original post by Ripper Phoenix

guys on the june 14R paper how is no. 4 part iii done? :smile:

I keep getting an extra (x+1) on the cos theita

its fine got it apparently my brain thinks 1/3 - 1 is -1/3 :tongue:

i feel like tomorrow i will be one of those guys doing 1 plus 1 on the calc just to be sure!

Reply 1610

User1686961

Original post by TheAnnabelle

Anybody can help me with Soloman Paper G question 2a ?

I really don't know how to do it at all!

Expand the 2 identities. then add them.

Reply 1611

frozo123

Original post by Ripper Phoenix

guys on the june 14R paper how is no. 4 part iii done? :smile:

I keep getting an extra (x+1) on the cos theita

take out (x-1)^-2/3 from the numerator so you have

( (x-1)^-2/3(-3sin(x+1) -cos(x) ) / (x+1)^2/3

so take the thing to the top it'll be (x+1)^-4/3
then put it in the bottom
edit: sorry just saw your post :smile:

Reply 1612

nayilgervinho

Original post by Ripper Phoenix

guys on the june 14R paper how is no. 4 part iii done? :smile:

I keep getting an extra (x+1) on the cos theita

u=3cosx, v=(x+1)^1/3, u'=-3sinx, v'=1/3(x+1)^-2/3

It should work then for quotient rule.

Reply 1613

User1686961

HEY GUYS!!!

Which is the hardest Solomon paper i need to do a paper. I've done em all.

someone reply thanks!

Reply 1614

adorablegirl1202

I need help with c3 jan 2007 7d

Reply 1615

Gome44

Original post by ThatGuyRik

HEY GUYS!!!

Which is the hardest Solomon paper i need to do a paper. I've done em all.

someone reply thanks!

Do these http://www.madasmaths.com/archive_iygb_practice_papers_c3_practice_papers.html

Reply 1616

TheAnnabelle

Original post by ThatGuyRik

Expand the 2 identities. then add them.

Thanks!

Sorry it was my bad but i meant to write F (not G)....idk where my head is....

Can anyone explain the answer?

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Screen Shot 2015-06-11 at 19.03.09.png12.3KB

Reply 1617

frozo123

Original post by TheAnnabelle

Thanks!

Sorry it was my bad but i meant to write F (not G)....idk where my head is....

Can anyone explain the answer?

Screen Shot 2015-06-11 at 19.02.55.png

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complete the square.

Reply 1618

User1686961

Original post by TheAnnabelle

Thanks!

Sorry it was my bad but i meant to write F (not G)....idk where my head is....

Can anyone explain the answer?

Screen Shot 2015-06-11 at 19.02.55.png

Attachment not found

Factorize is it using completing the square. We know the shape is going to be a parabola so that should make it easier.