Edexcel C3,C4 June 2013 Thread

ImageUploadedByStudent Room1371300323.071705.jpg

can someone please help me with 3)a) I know how to do it but I get the a wrong answer?
I get the coefficient of x^2 as 8/27 instead of 4/27 and x^3 as 40/243 instead of 40/729!
thank you

Posted from TSR Mobile

Is your simplified expansion like this? The x³ coefficient is probably from the same initial error.

Excuse horrible drawings.

(edited 10 years ago)

Untitled-1.jpg210.6KB

Reply 3581

physicso

13

Original post by MasterYi

dV/dh means it is with respect to h(height). So so it is the 'x' in the equation.

If it was dV/dr then 2πrh would be correct.

ahhhh your a life saver, yeah that makes sense thanks.

The question didn't actually say what to differentiate with respect to, but do you just choose which ever variable is changing? because the radius wasn't changing in the question

Reply 3582

nukethemaly

11

Original post by Myocardium

Yeah and all the other identities such as inegral of 1/ax+b = 1/a ln(ax+b)

I'm gonna make some notes on that after I revise for biology so I'll let you know

Reply 3583

MasterYi

Original post by physicso

ahhhh your a life saver, yeah that makes sense thanks.

The question didn't actually say what to differentiate with respect to, but do you just choose which ever variable is changing? because the radius wasn't changing in the question

They don't usually tell yo, so you have to make up you own.

Yes I'm assuming thats right, the height is the variable so it can change.

Reply 3584

task

Original post by MasterYi

Is your simplified expansion like this? The x³ coefficient is probably from the same initial error.

Excuse horrible drawings.

i completely forgot about the factorials when doing it so that was a stupid mistake by me! but thank you master yi :wink:

Reply 3585

cooldudeman

18

Can someone give a clear definition of induced fission

Posted from TSR Mobile

Reply 3586

MasterYi

Original post by cooldudeman

Can someone give a clear definition of induced fission

Posted from TSR Mobile

With numbers or neutrons?

Reply 3587

cooldudeman

18

Original post by MasterYi

With numbers or neutrons?

Neutrons and atomic numbers

Posted from TSR Mobile

Reply 3588

Myocardium

Original post by nukethemaly

I'm gonna make some notes on that after I revise for biology so I'll let you know

Okay thanks :smile:

Original post by cooldudeman

Can someone give a clear definition of induced fission

Posted from TSR Mobile

Do we need to know this for C4 :s-smilie:

Reply 3589

MasterYi

Original post by cooldudeman

Neutrons and atomic numbers

Posted from TSR Mobile

I was trying to say wrong thread.

Here's a physics thread which maybe able to help.
http://www.thestudentroom.co.uk/showthread.php?t=2244676

Reply 3590

Scorcher

1

C4 solomon B question 8b jesus christ that took longer than any question I've done before, so much working out :eek:

Haven't seen a vectors one like that before (with squared lambda etc), the same method applies but half way through I was convinced I was doing it wrong as it was way more than what you usually have to do, finally got there though :redface:

(edited 10 years ago)

Reply 3591

MAD Phil

Original post by jadecross

Why was this paper so much easier? I swear I could have got an A on this one. :frown:

If the UMS system works properly, the difficulty of the paper shouldn't make any real difference to your final grade. Perhaps you have got an A.

So, hard as it is to follow, the best advice is to stop worrying about the fact that you were given a hard paper, and just carry on with your life. (C4, for example? :wink:

)

Reply 3592

Minumi

I'm really stuck on q6a of C4 Solomon A. It's only a 4 marker so it shouldn't be too complicated, but I just DON'T UNDERSTAND AT ALL.

The question is to find the integral (don't know how to do the squiggle) of 2sin3xsin2x dx

:colondollar:

Reply 3593

EL77

7

Do we have to know the formulas for different areas and volumes such as cones and spheres off by heart? Or will the be given with the question if we need them?

Reply 3594

Scorcher

1

Original post by Minumi

I'm really stuck on q6a of C4 Solomon A. It's only a 4 marker so it shouldn't be too complicated, but I just DON'T UNDERSTAND AT ALL.

The question is to find the integral (don't know how to do the squiggle) of 2sin3xsin2x dx

:colondollar:

Use the identity cos(a) - cos(b) = -2sin(A+B/2)sin(A-B/2)

That's A+B all over 2 and A-B all over 2 btw.

Reply 3595

Knoyle quiah

Original post by Knoyle quiah

How to do the last part of this question??? can someone show me the diagram they get please, myne seems to be wrong or the mark scheme is wrong

someone help

Reply 3596

destinyx

Original post by Minumi

I'm really stuck on q6a of C4 Solomon A. It's only a 4 marker so it shouldn't be too complicated, but I just DON'T UNDERSTAND AT ALL.

The question is to find the integral (don't know how to do the squiggle) of 2sin3xsin2x dx

:colondollar:

Do cos(3x-2x) - cos(3x-2x) ie. (cox3xcos2x + sin3xsin2x) - (cos3xcos2x - sin3xsin2x) and work it out from there. There are similar questions to this in one of the exercises in the C4 text book. :smile:

I just did this paper the other day so happened to have my method close by. :smile:

Reply 3597

Myocardium

Guys I have a problem with my calculator (a normal everyday casio fx-85gt plus). I managed to press a couple of buttons all at once and I don't know what I've done but it's now come up as having TRUE/FALSE at the bottom of the screen. How do I bring it back to normal (and what would I press to bring up this function again (that I never knew existed)). :colondollar:

Reply 3598