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# AQA A2 Mathematics MPC4 Core 4 - 9th June 2015 [Discussion & unofficial markscheme] watch

1. (Original post by YoloSwagginz)
Minima and maximum occur as the cos graph changes like for cos it's max value is when cos is 1 and minima is cos = -1

So -r is min and r is max
Thanks.
One last question: for the questions where you expand an equation, there is sometime question that asks you for the range or something where the answer is like |x|<2, for example, I don't understand how they find out, please help.
2. last minute practice?

look at the links in post 2 in

http://www.thestudentroom.co.uk/show....php?t=3353445
Attached Images

3. (Original post by Mgdawber)
I haven't checked if this is right yet but this is how I would do it!Attachment 422901

It's right thank you so much!
4. for the questions where you expand an equation, there is sometime question that asks you for the range or something where the answer is like |x|<2, for example, I don't understand how they find out, please help
5. (Original post by hamza3256)
Thanks.
One last question: for the questions where you expand an equation, there is sometime question that asks you for the range or something where the answer is like |x|<2, for example, I don't understand how they find out, please help.

Binomial expansion okay so say you get given (3+x)^0.5 well to expand it using the formula you must divide by 3 so you get like 3^0.5(1+x/3)^0.5 now for a standard equation like (1+x)^0.5 the range is always -1 < x < 1 all you do now is sub x/3 for x so

-1 < x/3 < 1 and now that hoes to
-3<x<3

The modulus is just another way of writing the above so just stick to what I said you will be ok
6. Hi can anyone help me with how you prove sin3x, cos3x and tan3x using the addition formulas? Thanks!!!!
7. (Original post by YoloSwagginz)
Binomial expansion okay so say you get given (3+x)^0.5 well to expand it using the formula you must divide by 3 so you get like 3^0.5(1+x/3)^0.5 now for a standard equation like (1+x)^0.5 the range is always -1 < x < 1 all you do now is sub x/3 for x so

-1 < x/3 < 1 and now that hoes to
-3<x<3

The modulus is just another way of writing the above so just stick to what I said you will be ok
Thanks but I could not understand where do you get the x/3 from?
8. I'm going now, good luck to everyone.
9. (Original post by hamza3256)
Thanks but I could not understand where do you get the x/3 from?
Do you use the formula 1 + an ... Etc
10. (Original post by Cattie2312)
Hi can anyone help me with how you prove sin3x, cos3x and tan3x using the addition formulas? Thanks!!!!
Is there a paper that has this question cause I've never seen it
11. (Original post by YoloSwagginz)
Is there a paper that has this question cause I've never seen it
There isn't one, but people think it's going to come up. I don't know how you would tackle it exactly though.

sin3x = 2sin2xcosx
=4sinxcos^2x

Maybe?
12. (Original post by YoloSwagginz)
Do you use the formula 1 + an ... Etc
OH! I get it now. Thanks, I am actually very tired, so couldn't understand it, but now I do.

Gud luck for the exam!.
13. (Original post by hamza3256)
Thanks but I could not understand where do you get the x/3 from?

If you are given a problem like (3-x)^-1

In order to expand it you need a 1 instead of a 3 so in order to get rid of it in the bracket you simply divide out and then put the 3 outside the bracket with the same power sooo

(3^-1)(1-x/3)^-1 = (3-x)^-1
14. (Original post by 2014_GCSE)
There isn't one, but people think it's going to come up. I don't know how you would tackle it exactly though.

sin3x = 2sin2xcosx
=4sinxcos^2x

Maybe?
I'm pretty sure we don't get asked proofs and also to integrate or differentiate that will be easy
15. (Original post by 2014_GCSE)
There isn't one, but people think it's going to come up. I don't know how you would tackle it exactly though.

sin3x = 2sin2xcosx
=4sinxcos^2x

Maybe?
Well I'd write it as sin2xcosx * cos2xsinx

Now you need double angle for both cos and sin which is simply 2sinxcosx and cos^2x - sin^2x now sub them in then how far do you go? Cause now we can start using the basic sin^2 + cos^2 = 1
16. (Original post by 2014_GCSE)
There isn't one, but people think it's going to come up. I don't know how you would tackle it exactly though.

sin3x = 2sin2xcosx
=4sinxcos^2x

Maybe?
It's definitely come up at least once, you just do, for example cos3x = cos (2x+x) (for use in cos2xcosx-sin2xsinx) and solve as normal. It asks you to find it because sometimes we get asked to solve sin^2x, which you need to rearrange your solution to find and then integrate that
17. (Original post by 2014_GCSE)
There isn't one, but people think it's going to come up. I don't know how you would tackle it exactly though.

sin3x = 2sin2xcosx
=4sinxcos^2x

Maybe?

Usually the question will ask show that or similar.
18. (Original post by 2014_GCSE)
There isn't one, but people think it's going to come up. I don't know how you would tackle it exactly though.

sin3x = 2sin2xcosx
=4sinxcos^2x

Maybe?
Hi! I just showered and I decided to check the thread on my phone one last time before I go to sleep, so this is my actual final post for today^^.

I don't believe it's ever been in an exam but it's definitely in the textbook.

It's actually pretty simple to solve; you start by rewriting sin3x as sin(x + 2x). Then you just use the formula in the booklet for sin(A + B) and rewrite sin(x + 2x) in that form (where A = x and B = 2x). After that point it all becomes standard stuff .

Alright! Sleep (for real)! Good luck guys, I guess I'll see everyone on here after the exam.
It's definitely come up at least once, you just do, for example cos3x = cos (2x+x) (for use in cos2xcosx-sin2xsinx) and solve as normal. It asks you to find it because sometimes we get asked to solve sin^2x, which you need to rearrange your solution to find and then integrate that
It's never came up in june 2010 to present, I've only done a few of the 2005 - jan 2010 ones
20. In 40 minutes it's my birthday

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