AQA A2 MFP3 Further Pure 3 – 18th May 2016 [Exam Discussion Thread]

Can someone explain where the minus in the 1/3 comes from in this integral? Almost certain I'm just doing something stupid but can't quite get the answer myself.

Posted from TSR Mobile

It's just reversing the chain rule. You have a function (call it f) of cosx multiplied by the derivative of cosx and so you can simply integrate f(cosx) with respect to cosx.

Reply 181

Rabadon

11

Original post by Adam_98

Can someone explain where the minus in the 1/3 comes from in this integral? Almost certain I'm just doing something stupid but can't quite get the answer myself.

Posted from TSR Mobile

I know others have answered but will also work if you let u=2+cosx and then integrate by substitution

Reply 182

Adam_98

2

Original post by Qcomber

The derivative of cosx is -sinx. So -1/3 needed to cancel the -3 when you differentiate your answer to obtain the original integrand.

Thanks, made the silly mistake of using sinx as the derivative of cosx not -sinx

Posted from TSR Mobile

Reply 183

Roxanne18

9

After last years horrible polar question (or I thought it was anyway)
is it likely that polar will be the challenging one again do you think ?

Reply 184

Hjyu1

2

Original post by Roxanne18

After last years horrible polar question (or I thought it was anyway)
is it likely that polar will be the challenging one again do you think ?

Probably but as the questions get more difficult the grade boundaries should drop

Reply 185

-jordan-

5

Original post by Roxanne18

After last years horrible polar question (or I thought it was anyway)
is it likely that polar will be the challenging one again do you think ?

If AQA feel like being creative then it'll be the polar coordinates question for sure, depends how they're feeling.

Reply 186

IrrationalRoot

20

Original post by -jordan-

If AQA feel like being creative then it'll be the polar coordinates question for sure, depends how they're feeling.

AQA will definitely be creative with this one :smile:

. I can tell we'll have a couple of really nice Qs; looking forward to this paper.

One thing they really shouldn't try to be creative with is the Euler numerical method stuff. That would just be stupid.

Reply 187

-jordan-

5

Original post by IrrationalRoot

AQA will definitely be creative with this one :smile:

. I can tell we'll have a couple of really nice Qs; looking forward to this paper.

One thing they really shouldn't try to be creative with is the Euler numerical method stuff. That would just be stupid.

Yeah I have this fear that all of a sudden they'll test us on how the improved Euler method's work after so many questions which just need you to be able to use a calculator. Gonna spend a little bit of time going over it.

Reply 188

JME_CHG

8

Original post by Hjyu1

Probably but as the questions get more difficult the grade boundaries should drop

Are you sure about that? They went up from 2014 to 2015... :/

Reply 189

JME_CHG

8

Original post by IrrationalRoot

AQA will definitely be creative with this one :smile:

. I can tell we'll have a couple of really nice Qs; looking forward to this paper.

One thing they really shouldn't try to be creative with is the Euler numerical method stuff. That would just be stupid.

They will also give us 10 Qs instead of 7-8?

Reply 190

Adam_98

2

Original post by -jordan-

Yeah I have this fear that all of a sudden they'll test us on how the improved Euler method's work after so many questions which just need you to be able to use a calculator. Gonna spend a little bit of time going over it.