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Edexcel Core 3 - 21st June 2016 AM

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Ah I thought so. complete the square on x^2 + 6x + 6 for a simpler problem

yep, i've looked at it again, it's much simpler now that i've come back to it, hopefully i won't get these mindblocks tomorrow

Reply 681

math42

Original post by Don Pedro K.

Ah so we have to consider the possibility that x could = 0 since x is any real number?

Yes. Then once you've counted the solution x = 0 you implicitly assume x =/= 0 and deduce what else x can be
Never divide unless you're sure it's by something non-zero

Reply 682

kkboyk

Just started C3 revision today. Hoping that all the questions are straight forward. :tongue:

Reply 683

Music With Rocks

What are the hardest questions any of you have found in the past papers? I don't have time to do them all so would like to try the trickiest questions :smile:

thank you

Reply 684

-Bex-

Original post by Ainsleyy

In the june 2015 c3 paper can anyone tell me how they do question 8 part b? Part a is pretty hard too but I can see what they did.

(cosA + sinA)/(cosA - sinA) = 1/2

2cosA + 2sinA = cosA - sinA

cosA = -3sinA

tanA = -1/3

Reply 685

Mattematics

Original post by SeanFM

No worries, everyone hits this brick wall at one point or another in Maths.

There is no such law that you can deal with that. The laws of logs are that ln(ab) = ln(a) + ln(b) and ln(a/b) = ln(a) - ln(b), and ln(a^b) = blna.

So.. nothing helps. Logs aren't linear - ln(a+b) is not the same as ln(a) + ln(b).

So to clarify, when you take logs you consider the whole of each side as one big group rather than doing it term by term?

i.e. y = ax + b
lny = ln(ax + b) rather than lny = ln(ax) + lnb

My mind is absolutely fried after Physics earlier :P

Reply 686

keres

Original post by Pablo Picasso

k > Turning points

Hi, thanks for your reply
But why does k have anything to do with the turning points? x

Reply 687

Mattematics

Original post by kkboyk

Just started C3 revision today. Hoping that all the questions are straight forward. :tongue:

No chance. Prepare for more p^2 + qr + c PTSD.

Reply 688

-Bex-

Original post by Music With Rocks

What are the hardest questions any of you have found in the past papers? I don't have time to do them all so would like to try the trickiest questions :smile:

thank you

June 2013 has the hardest questions in general if you want to pick and choose your weakest topics from there is a good start

Reply 689

BrainJuice

Does anyone know how you find the range of this?:

x/(x-2) x is true for all real values, x > 2

Reply 690

Ainsleyy

Original post by SeanFM

after the first line of b (keeping in mind you want theta on its own somehow)

Multiply both sides by 2 and (costheta - sintheta).

Then take 1 * costheta away from both sides, take away 2 *sintheta away from both sides. (You could bring them to the same side but it'd be pointless).

So you have that 1costheta = -3sintheta.

Divide both sides by 3costheta to give you what they've got.

Of course!! Thanks! I've told my self dont divide when doing triq questions as sometimes I get rid of an answer because I divide it out. I guess I just need to remember that you dont divide only when you can factorise instead.

Reply 691

Kevin De Bruyne

Original post by Mattematics

Correct - you must always take the logs of both sides rather than the logs of individual terms.

Having examps in quick succession sucks :frown:

Reply 692

bat_man

I dont know whether im happy or sad about getting 61 in the june 2013 paper. Dont feel right.

Reply 693

ememoville

Original post by Pablo Picasso

k > Turning points

Consider where you can draw a horizontal line and get two values.

So between the turning point (y co, ordinate of A and 0) that's the range for k

Reply 694

Music With Rocks

Original post by -Bex-

June 2013 has the hardest questions in general if you want to pick and choose your weakest topics from there is a good start

Thank you, literally just finished June 2013 haha :tongue:

were certainly some awkward ones, grade boundaries where shockingly low for C3 that year

Reply 695

Kevin De Bruyne

Original post by Ainsleyy

Indeed. Never divide in trig to cancel. You can add or take away things (as chances are, it'll be made up somewhere else) but never divide TO CANCEL. Dividing both sides by cos to give tan is fine.

Reply 696

Kevin De Bruyne

Original post by bat_man

I dont know whether im happy or sad about getting 61 in the june 2013 paper. Dont feel right.

61 in that paper is very good, you're likely to get a lot higher in the actual one.

Reply 697

cookiemonster15

Original post by bat_man

I dont know whether im happy or sad about getting 61 in the june 2013 paper. Dont feel right.

That was a really difficult paper, it was 57 for an A* and 50 (I think) for an A.

Reply 698

Ainsleyy

Original post by Music With Rocks

What are the hardest questions any of you have found in the past papers? I don't have time to do them all so would like to try the trickiest questions :smile:

thank you

A good thing you can do is the gold papers from physicsandmathstutor. They are a compilation of all hard Q's from past papers. Otherwise most of June 2013 was more challenging especially Q8. June 2015 Q 8 is quite hard.