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# How to use the factor formuale for integration ? watch

1. Hello there, someone said that instead of using the addition formuale , you could use the factor formulae (P+Q) to make integration easier to do...but i dont know how to do this and is currently struggling with it...pls help me do this example:

2sin2xsin5x
2. (Original post by laurawoods)
Hello there, someone said that instead of using the addition formuale , you could use the factor formulae (P+Q) to make integration easier to do...but i dont know how to do this and is currently struggling with it...pls help me do this example:

2sin2xsin5x
To be honest using integration by parts is the best method of solving these problems.
Learning all the Formulae is a lot of effort but and proving them is even more.
3. (Original post by laurawoods)

2sin2xsin5x

is given in the formula booklet
4. (Original post by TenOfThem)

is given in the formula booklet
hello there pls can u talk in terms of P and Q since that is the way it is laid out in the formula sheets and hence i would find that way easier....
cheerios!
5. (Original post by laurawoods)
hello there pls can u talk in terms of P and Q since that is the way it is laid out in the formula sheets and hence i would find that way easier....
cheerios!
I thought you did edexcel
6. (Original post by TenOfThem)
I thought you did edexcel
yes of course I do edexcel, sorry noticed now in the formuale sheet that it is in terms of A and B but in the TEXTBOOK in terms of P and Q,,pls can u do P and Q ...sorry for rude lang...
7. (Original post by laurawoods)
yes of course I do edexcel!
Then, what are you talking about re P and Q?
8. (Original post by laurawoods)
yes of course I do edexcel, sorry noticed now in the formuale sheet that it is in terms of A and B but in the TEXTBOOK in terms of P and Q,,pls can u do P and Q ...sorry for rude lang...
So, given that you are going to be using the formula book in the exam ... use the formula that you will get there
9. If you're not going to be bothered to learn how to apply the formulas in your formula packet, you might as well ignore them.

But anyways:

Let P=(A+B)/2 and Q=(A-B)/2

Find A and B, and your formula for 2sinPsinQ will come out.
10. (Original post by aznkid66)
If you're not going to be bothered to learn how to apply the formulas in your formula packet, you might as well ignore them.

But anyways:

Let P=(A+B)/2 and Q=(A-B)/2

Find A and B, and your formula for 2sinPsinQ will come out.
hello do what do we do after this stage:
A+B/ 2 = 5
A-B / 2 = 2

Therefore adding together gives, A= 7 and B= 3

then cos7x-cos3x ....BUT THEN WHAT I AM REALLY STUCK WITH IS HOW TO ADJUST THE CONSTANTS IN FRONT....
11. (Original post by laurawoods)
hello do what do we do after this stage:
A+B/ 2 = 5
A-B / 2 = 2

Therefore adding together gives, A= 7 and B= 3

then cos7x-cos3x ....BUT THEN WHAT I AM REALLY STUCK WITH IS HOW TO ADJUST THE CONSTANTS IN FRONT....
Are you saying that you do not know that

12. (Original post by TenOfThem)
Are you saying that you do not know that

btw , you have got that wrong...no minus sign

and i am not talking about that
13. (Original post by TenOfThem)
Are you saying that you do not know that

on here we have got

2sin2xsin5x
what do we have to do with the two>
14. (Original post by laurawoods)
btw , you have got that wrong...no minus sign
good spot

and i am not talking about that
So, what are you talking about
15. (Original post by laurawoods)
on here we have got

2sin2xsin5x
what do we have to do with the two>
You have used the 2 already

16. (Original post by TenOfThem)
You have used the 2 already

how do u say that i ave used the 2 already>>>
17. (Original post by laurawoods)
how do u say that i ave used the 2 already>>>
Go back over your work ... you must have used the 2 ... it is in the formula
18. (Original post by TenOfThem)
Go back over your work ... you must have used the 2 ... it is in the formula
19. (Original post by laurawoods)
yes, there are a few (2 or 3 depending on how you write it)

which one in particular are you worried about
20. (Original post by TenOfThem)
yes, there are a few (2 or 3 depending on how you write it)

which one in particular are you worried about
Hello there,

So for example when u do a question like

integrating :

sin6xsin2x

there is a MINUS sign and a 2 which is coming as extra ...so what do we do?

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