C4 maths

Hello, this question of mine is related to integration unit of C4:

Integration using substitution,
When we end up with u as the final thing , and the substitution we made initially was x=tan u , how do we get the answer back in terms of x ?

because we surely cannot leave the final answer in forms of u right?

Reply 1

joostan

13

Original post by laurawoods

Hello, this question of mine is related to integration unit of C4:

Integration using substitution,
When we end up with u as the final thing , and the substitution we made initially was x=tan u , how do we get the answer back in terms of x ?

because we surely cannot leave the final answer in forms of u right?

For definite integrals yes. If indefinite then no, you must convert back using arctan.

Original post by laurawoods

Hello, this question of mine is related to integration unit of C4:

Integration using substitution,
When we end up with u as the final thing , and the substitution we made initially was x=tan u , how do we get the answer back in terms of x ?

because we surely cannot leave the final answer in forms of u right?

u=\tan^{-1}x

Reply 3

laurawoods

OP

8

Original post by Mr M

u=\tan^{-1}x

thanks to both answers- joostan and Mr M. :smile:

!

Reply 4

joostan

13

Original post by laurawoods

thanks to both answers- joostan and Mr M. :smile:

!

np

Reply 5

laurawoods

OP

8

Original post by joostan

np

Pls can u answer this maths question of mine :smile:

Hello, if we have something like y+1 to integrate, don't we get y^2/2 + y

Pls can you look at the solution to question no 4 on this paper:
http://papers.xtremepapers.com/Edexcel/Advanced%20Level/Mathematics/Subject%20Sorted/C4/Elmwood%20Papers/Elmwood%20H%20MS.pdf

They went about a different way ...do u think my method would be fine ...because I got the same answer as them >...

Reply 6

joostan

13

Original post by laurawoods

Pls can u answer this maths question of mine :smile:

Hello, if we have something like y+1 to integrate, don't we get y^2/2 + y

Pls can you look at the solution to question no 4 on this paper:
http://papers.xtremepapers.com/Edexcel/Advanced%20Level/Mathematics/Subject%20Sorted/C4/Elmwood%20Papers/Elmwood%20H%20MS.pdf

They went about a different way ...do u think my method would be fine ...because I got the same answer as them >...

If you get the same answer then I imagine its fine.
You'll have to ask MrM

Original post by Mr M

...

to be 100% sure but I think they should have put:

\int y + 1 \ d(y+1) = - \int x -2 \ d(x-2)

(edited 11 years ago)

Reply 7

laurawoods

OP

8

Original post by Mr M

u=\tan^{-1}x

Hello Mr M , Joostan asked me to ask you about this:
If we have something like y+1 to integrate, don't we get y^2/2 + y

Pls can you look at the solution to question no 4 on this paper:
http://papers.xtremepapers.com/Edexc...d%20H%20MS.pdf

They went about a different way ...do u think my method would be fine ...because I got the same answer as them >...

Reply 8

davros

16

Original post by laurawoods

Pls can u answer this maths question of mine :smile:

Hello, if we have something like y+1 to integrate, don't we get y^2/2 + y

Pls can you look at the solution to question no 4 on this paper:
http://papers.xtremepapers.com/Edexcel/Advanced%20Level/Mathematics/Subject%20Sorted/C4/Elmwood%20Papers/Elmwood%20H%20MS.pdf

They went about a different way ...do u think my method would be fine ...because I got the same answer as them >...

both methods are fine - they've just used "recognition" because

d/dy(y+1)^2 = 2(y+1)

Original post by laurawoods

Hello Mr M , Joostan asked me to ask you about this:
If we have something like y+1 to integrate, don't we get y^2/2 + y

Pls can you look at the solution to question no 4 on this paper:
http://papers.xtremepapers.com/Edexc...d%20H%20MS.pdf

They went about a different way ...do u think my method would be fine ...because I got the same answer as them >...