Edexcel C4 June 2014- OFFICIAL THREAD

Can anyone help me with a question, it's Question 2 from June 2013 (the r paper).

I apparently don't know how to differentiate 3^(x-1).

I've searched for resources and apparently I must do ln(y) = ln(3^x-1), but now I am confused as if I differentiate I get

1/y = (x-1)/3, yet the answer is simply 3^(x-1)ln(3)

here's a couple of ways to do the diff of y=a^x

http://youtu.be/9hhcwU9d9u8

hth

regards
:cool:

Reply 581

begbie68

16

(Original post by begbie68)
Hey.
Thanks for posting this up. Quite a challenge to get the vid completed.

http://youtu.be/DJawctqrIcw

Hope it helps
(read the comment to see the 'deliberate' errors!)

:cool:

PRSOM

(Original post by May-o2q)
Ohhh god, is a question like this usually come up in the exam?

Posted from TSR Mobile
I thought that! I really hope not. That's a really hard question.

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

It IS a really tough question. Took me some time to get it on screen, and I still made some mistakes - confusing the words "integration" and "differentiation" . . . D'Oh!!!

I would suggest this is NOT a past Edexcel question, and made valid comments on screen that it's unlikely to see a question like this on a test from Edexcel.
However, it IS instructional in various, relevant ways.

Thanks for the comments.

:cool:

Reply 582

Aamina786

Is it that hard to get 90 + on c4?

Reply 583

begbie68

16

Original post by Undisclosed 15

Can someone help me with 9a please. The lines are perpendicular so when you multiply the vectors they equal 0. I thought you would multiply OL and LM as they are both in a direction towards the angle but the solutionbank multiplied OL an LM.

Help please?

Posted from TSR Mobile

tricky little point to get the right vector at the beginning

http://youtu.be/Xh2gt6oo5Ac

thanks for posting the question.
hope this helps

:cool:

Reply 584

jtbteddy

5

Original post by Mutleybm1996

How?

ImageUploadedByStudent Room1402959853.121827.jpg

Posted from TSR Mobile

3 = ln(e³) bcoz if you'd take the power down, youd get 3ln(e) , right? and ln(e) = 1, so 3ln(e) is effectively 3

Reply 585

May-o2q

14

Guys, what do you suggest? To do past paper; gold,silver,bronze paper, practice paper? I don't kno where to start now. Done 1 practice paper, quite a lot of hard question. :frown:

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Reply 586

Mutleybm1996

19

Original post by jtbteddy

3 = ln(e³) bcoz if you'd take the power down, youd get 3ln(e) , right? and ln(e) = 1, so 3ln(e) is effectively 3

Why no 1/5?

Posted from TSR Mobile

Reply 587

hcooke123

2

How would you find ∫(x-1)(5-x)^0.5 dx between x=1 and x=5

Reply 588

username1129244

15

Original post by hcooke123

How would you find ∫(x-1)(5-x)^0.5 dx between x=1 and x=5

By parts and differentiate the x-1 bit

Reply 589

Wilsoncw1997

13

Original post by May-o2q

Guys, what do you suggest? To do past paper; gold,silver,bronze paper, practice paper? I don't kno where to start now. Done 1 practice paper, quite a lot of hard question. :frown:

Posted from TSR Mobile

Do them all, start from practice as they are hardest. Then ranked paper, after that 2013-14 papers.

Reply 590

Freddy-Francis

9

Original post by Dilzo999

Just hope examsolutions isn't down.

I bought the app for a pound :smile:

Reply 591

Gurissi

Original post by Undisclosed 15

The solutionbank multiplied OL and LM

Posted from TSR Mobile

Then I have no idea. :'(

Reply 592

Pro Crastination

19

Original post by Elcor

Hit the nail on the hammer there - it's where having a calculator that does numerical integration/differentiation comes in handy. My one's limited in that it can't do anything parametric though.

Ah, just realised mine can too :biggrin:

Woo. Not sure about solving differential equations, but I can differentiate with it.

(edited 9 years ago)

Reply 593

R2D2.

5

http://examsolutions.net/a-level-maths-papers/Edexcel/Core-Maths/Core-Maths-C4/2012-January/questions/q8.gif

can someone explain part b to me? The mark scheme and the guy factors out 1/5 but I got 1/5 ln(5p).

To put into context, I had to integrate 1/5p and 1/5(5-p) and I got 1/5 ln5p and 1/5 ln5(5-p) . Why is my method not correct?

Reply 594

lmorgan95

8

Original post by R2D2.

http://examsolutions.net/a-level-maths-papers/Edexcel/Core-Maths/Core-Maths-C4/2012-January/questions/q8.gif

can someone explain part b to me? The mark scheme and the guy factors out 1/5 but I got 1/5 ln(5p).

To put into context, I had to integrate 1/5p and 1/5(5-p) and I got 1/5 ln5p and 1/5 ln5(5-p) . Why is my method not correct?

The second integral is incorrect- it should integrate to (-1/5)ln(5-p)

Reply 595

recurring500

11

Original post by Undisclosed 15

Can someone help me with 9a please. The lines are perpendicular so when you multiply the vectors they equal 0. I thought you would multiply OL and LM as they are both in a direction towards the angle but the solutionbank multiplied OL an LM.

Help please?

Posted from TSR Mobile

Could you post the answers please?

Reply 596

Jaydude

11

Is it worth doing the last question first and/or work your way backwards through the paper??

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Reply 597

Meriam_xx

someone please help me find the particular solutions of this equation

dy/dx = sinxcos^2x where y=0 and x=pi/3

Reply 598

Aamina786

I hate connected rates of change :confused:

Reply 599

Pro Crastination

19

Original post by Jaydude

Is it worth doing the last question first and/or work your way backwards through the paper??

Posted from TSR Mobile

If you are supremely confident, yes. I find that pretty much all exam boards put their easier questions at the start as a means of calming down nervous students, however. I never dare even look at the following question until I'm finished with the one I am working on, if I spot that it's something I can't work out I panic even more, as I realise I'm going to get two questions wrong in a row :frown:

Edexcel C4 June 2014- OFFICIAL THREAD

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