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How to integrate cos 2x

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Reply 20

ellishnoo

So was the answer meant to be 1/2 Sin 2x +c

yes

So does everyone agree is the answer 0.5 sin 2 x +c

1/2 sin2x + c

YEYyyyyyyyyyyyyyy thank you everyone

Reply 25

130ss

ellishnoo

Is the intigration of cos 2 x
2 sin x+c
thanks
Elli

nah blad... its -1/2sin2x +c

Reply 26

130ss

The Muon

yes

lol how can you be accepted for mmaths at warwick when you didnt even know that

Reply 27

giran

If they ask you to integrate and find out the area within a boundary, no.
Always right + c at the end though, say for example.

y = 3x^2 + 3x + 10
dy/dx = 6x + 3 right?

If you differentiated dy/dx, you'd get 3x^2 + 3x, but thats as far as you can go, however, you know the original question has +10 on the end. Therefore whenever you integrate, you add +c to indicate there could have been a real value.

Reply 28

x_dwin_ffeimys_x

ellishnoo

Is the intigration of cos 2 x
2 sin x+c
thanks
Elli

it gets dived with two I though...but I havnt red the repplies,

Reply 29

ticktockclock

ellishnoo

So was the answer meant to be 1/2 Sin 2x +c

Yes it is and don't forget im the one who said it first, everyone else was leading you down the wrong track.

Reply 30

The Muon

130ss

lol how can you be accepted for mmaths at warwick when you didnt even know that

don't even know what? little confused here!
I'm pretty sure Warwick offer damn near everyone - the test comes in attaining the entrance grades.

Reply 31

130ss

The Muon

don't even know what? little confused here!
I'm pretty sure Warwick offer damn near everyone - the test comes in attaining the entrance grades.

no for maths you need STEP for warwick and AAA for maths. its quite competitive warwick for maths.

Reply 32

sonofdot

130ss

no for maths you need STEP for warwick and AAA for maths. its quite competitive warwick for maths.

You'd have thought the Muon would know, since he has an offer and everything...

But since you seem unconvinced:

http://www2.warwick.ac.uk/fac/sci/maths/admissions/ug/offer/

We make a standard offer to almost all applicants with A and AS-Level qualifications, and this is explained below

The difficulty is in making the grades when you have the offer...

Reply 33

130ss

sonofdot

You'd have thought the Muon would know, since he has an offer and everything...

But since you seem unconvinced:

The difficulty is in making the grades when you have the offer...

wow i am surprised. i thought it was quite hard to get into warwick.. for straight eco it is anyway..
there policy with maths is quite lenient.. STEP papers are quite hard.

Reply 34

Trampmaster90

see if this helps, cos(ax + b)dx = 1/a sin(ax + b) + c
so in this case itd be 1/2sin2x hope that helps

Reply 35

The Muon

130ss

wow i am surprised. i thought it was quite hard to get into warwick.. for straight eco it is anyway..
there policy with maths is quite lenient.. STEP papers are quite hard.

The idea behind the warwick maths entry is they give everyone an offer but not everyone will meet the offer. It is quite hard to get into warwick. Sounds to me like your confusing getting an offer and actually getting in.

Reply 36

Krush

The Muon

don't even know what? little confused here!

He believes that you got the answer to the OPs question wrong... :o:

Reply 37

11flon

I know this is a really old thread but I was wondering if anyone could explain this to me really simply as I don't really understand the above posts :frown:

ok say if we use chain rule but for integrating, with y = cos(u) and u = 2x

doesn't the integral of 2x =x²? which would make the answer sinx² rather than (sin2x)/2.

Or even if you divide the whole function by 2, wouldn''t it become (sin2x²)/2? I don't understand why we don't seem to raise the power of x by one to make it x²?

(Edited as accidentally said derivative instead of integral and people got confused...)

(edited 11 years ago)

Reply 38

BabyMaths

Original post by 11flon

u = 2x

doesn't du/dx =x²?

No. du/dx = 2

Reply 39

steve2005

Original post by 11flon

I know this is a really old thread but I was wondering if anyone could explain this to me really simply as I don't really understand the above posts :frown:

ok say if we use chain rule but for integrating, with y = cos(u) and u = 2x

doesn't du/dx =x²? which would make the answer sinx² rather than (sin2x)/2.

Or even if you divide the whole function by 2, wouldn''t it become (sin2x²)/2? I don't understand why we don't seem to raise the power of x by one to make it x²?