# Differential equation question.

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Can anyone illustrate the method for how to do this question.

Reputation points to any person who can show me a fully worked solution, on the method to solve this question. I can the first few parts. But beyond that i get stuck.

Cheers

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#2

(Original post by

Can anyone illustrate the method for how to do this question.

Reputation points to any person who can show me a fully worked solution.

Cheers

Posted from TSR Mobile

**stealth_writer**)Can anyone illustrate the method for how to do this question.

Reputation points to any person who can show me a fully worked solution.

Cheers

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You differentiate

You spot that Cos(y) = the root of (1-sin^2x)

I could give you a fully worked answer so I expect the Rep points in spite of the fact that I will not since I think you will learn more if you think it through yourself

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#3

(Original post by

You start with Sin(y) = x

You differentiate

You spot that Cos(y) = the root of (1-sin^2x)

I could give you a fully worked answer so I expect the Rep points in spite of the fact that I will not since I think you will learn more if you think it through yourself

**TenOfThem**)You start with Sin(y) = x

You differentiate

You spot that Cos(y) = the root of (1-sin^2x)

I could give you a fully worked answer so I expect the Rep points in spite of the fact that I will not since I think you will learn more if you think it through yourself

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**TenOfThem**)

You start with Sin(y) = x

You differentiate

You spot that Cos(y) = the root of (1-sin^2x)

I could give you a fully worked answer so I expect the Rep points in spite of the fact that I will not since I think you will learn more if you think it through yourself

i can do all of that bit my friend. I can get up to the bit where we show that y=ksin-1x satisfies the differential equation.

It is the bit beyond (in other word beyond the "in this particular case" part) that i cannot do despite struggling for hours.

I too also agree with your sentiment in your reply; however I have exhausted all options on this question, and tsr has been my last resort. Please could you show me how to do this question ...... so that I can work backwards. Sometimes one can learn more working backwards than they did working forwards if you know what i mean.

P. s this isn't coursework or homework- rather independent study/revision.

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#5

(Original post by

Hi,

i can do all of that bit my friend. I can get up to the bit where we show that y=ksin-1x satisfies the differential equation.

It is the bit beyond (in other word beyond the "in this particular case" part) that i cannot do despite struggling for hours.

I too also agree with your sentiment in your reply; however I have exhausted all options on this question, and tsr has been my last resort. Please could you show me how to do this question ...... so that I can work backwards. Sometimes one can learn more working backwards than they did working forwards if you know what i mean.

P. s this isn't coursework or homework- rather independent study/revision.

**stealth_writer**)Hi,

i can do all of that bit my friend. I can get up to the bit where we show that y=ksin-1x satisfies the differential equation.

It is the bit beyond (in other word beyond the "in this particular case" part) that i cannot do despite struggling for hours.

I too also agree with your sentiment in your reply; however I have exhausted all options on this question, and tsr has been my last resort. Please could you show me how to do this question ...... so that I can work backwards. Sometimes one can learn more working backwards than they did working forwards if you know what i mean.

P. s this isn't coursework or homework- rather independent study/revision.

If so, you really should be spending

**at least**2 days on the question before seeking any guidance.

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(Original post by

Judging by the question style and content... this is STEP III question?

If so, you really should be spending

**SamKeene**)Judging by the question style and content... this is STEP III question?

If so, you really should be spending

**at least**2 days on the question before seeking any guidance.Can you do this question?

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#7

Here's a clue:

Try substituting .

(Justification for the above statement: because the solution is assumed to be unique [a proof of that would be a dependency of any further results regarding sin(3x)], the statement is true for all x).

Try substituting .

(Justification for the above statement: because the solution is assumed to be unique [a proof of that would be a dependency of any further results regarding sin(3x)], the statement is true for all x).

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Can you elaborate a bit more/actually show me.

The best way to show me would be for you to do the worked solution on a piece of paper and then take a photo of your working. It's pretty easy to do in the mobile phone if you the tsr app

The best way to show me would be for you to do the worked solution on a piece of paper and then take a photo of your working. It's pretty easy to do in the mobile phone if you the tsr app

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#9

(Original post by

Can you elaborate a bit more/actually show me.

The best way to show me would be for you to do the worked solution on a piece of paper and then take a photo of your working. It's pretty easy to do in the mobile phone if you the tsr app

**stealth_writer**)Can you elaborate a bit more/actually show me.

The best way to show me would be for you to do the worked solution on a piece of paper and then take a photo of your working. It's pretty easy to do in the mobile phone if you the tsr app

Spoiler:

Show

Apologies for the lack of clarity (hastily writing it down as well as a rubbish phone camera ). The first image contains the first part (with the second bit at the top right corner), and the second image contains the bit which you were asking about (the last part).

EDIT:

I put the solution in latex because it's better like that:

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#10

**SamKeene**)

Judging by the question style and content... this is STEP III question?

If so, you really should be spending

**at least**2 days on the question before seeking any guidance.

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(Original post by

Since you asked:

Apologies for the lack of clarity (hastily writing it down as well as a rubbish phone camera ). The first image contains the first part (with the second bit at the top right corner), and the second image contains the bit which you were asking about (the last part).

EDIT:

I put the solution in latex because it's better like that:

**felamaslen**)Since you asked:

Spoiler:

Show

Apologies for the lack of clarity (hastily writing it down as well as a rubbish phone camera ). The first image contains the first part (with the second bit at the top right corner), and the second image contains the bit which you were asking about (the last part).

EDIT:

I put the solution in latex because it's better like that:

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My friends on TSR.

Due to the success of the last solution of my last problems could you guys help me out with another tricky question please. In the same manner as before (a worked solution).

Once again. Working backwards is much more fruitful IMO sometimes than working forwards

rep points to anyone who helps

Posted from TSR Mobile

Due to the success of the last solution of my last problems could you guys help me out with another tricky question please. In the same manner as before (a worked solution).

Once again. Working backwards is much more fruitful IMO sometimes than working forwards

rep points to anyone who helps

Posted from TSR Mobile

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(Original post by

It's almost, but not quite, identical to STEP I 1999 Q7

**davros**)It's almost, but not quite, identical to STEP I 1999 Q7

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#14

(Original post by

Hmmm. thanks for pointing this out. Is my above post a step paper question as well?

**stealth_writer**)Hmmm. thanks for pointing this out. Is my above post a step paper question as well?

(Original post by

My friends on TSR.

Due to the success of the last solution of my last problems could you guys help me out with another tricky question please. In the same manner as before (a worked solution).

Once again. Working backwards is much more fruitful IMO sometimes than working forwards

rep points to anyone who helps

Posted from TSR Mobile

**stealth_writer**)My friends on TSR.

Due to the success of the last solution of my last problems could you guys help me out with another tricky question please. In the same manner as before (a worked solution).

Once again. Working backwards is much more fruitful IMO sometimes than working forwards

rep points to anyone who helps

Posted from TSR Mobile

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(Original post by

I don't recognize it, but then I only recognized the last one because I remembered doing it a couple of months ago!

That's not really how TSR works! You should have a go at this question and post your working when you get stuck so that someone can help you move forwards. How far have you got with this particular question?

**davros**)I don't recognize it, but then I only recognized the last one because I remembered doing it a couple of months ago!

That's not really how TSR works! You should have a go at this question and post your working when you get stuck so that someone can help you move forwards. How far have you got with this particular question?

I understand your sentiment but i must stress i have tried this question and reached a brick wall. Hence, why i am on tsr.

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#16

(Original post by

Can do the first 1/3. But no further. And tsr needs to understand that not all people learn the same way.

I understand your sentiment but i must stress i have tried this question and reached a brick wall. Hence, why i am on tsr.

**stealth_writer**)Can do the first 1/3. But no further. And tsr needs to understand that not all people learn the same way.

I understand your sentiment but i must stress i have tried this question and reached a brick wall. Hence, why i am on tsr.

Post your working so far and we'll take it from there

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#17

(Original post by

..

**stealth_writer**)..

Show your working. TSR is not a homework service.

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(Original post by

Desperation is not an attractive quality.

Show your working. TSR is not a homework service.

**Mr M**)Desperation is not an attractive quality.

Show your working. TSR is not a homework service.

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#19

(Original post by

this isn't homework .

**stealth_writer**)this isn't homework .

So I imagine the bit you can't do is to derive the reduction formula.

Integrate by parts.

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(Original post by

Of course it isn't.

So I imagine the bit you can't do is to derive the reduction formula.

Integrate by parts.

**Mr M**)Of course it isn't.

So I imagine the bit you can't do is to derive the reduction formula.

Integrate by parts.

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