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# Differentiation question

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1. Ok so the first part of the question is x = 3sin y find DX/DY in terms of Y
I got 3cos y which is right, then it asked for me to find DY/DX in terms of Y, i then got 1/3 Sec Y, the next part is hence show DY/DX = 1/Root 9 - x to the power of 2, I cant do this part I dont know how to get from 1/3 Sec y to that?
2. (Original post by SunDun111)
Ok so the first part of the question is x = 3sin y find DX/DY in terms of Y
I got 3cos y which is right, then it asked for me to find DY/DX in terms of Y, i then got 1/3 Sec Y, the next part is hence show DY/DX = 1/Root 9 - x to the power of 2, I cant do this part I dont know how to get from 1/3 Sec y to that?
Hint: .
3. (Original post by joostan)
Hint: .
Ey but, isn't it asking me to get from 1/3 Sec y to 1/ Root 9 - x to the power of 2 ,
4. (Original post by SunDun111)
Ey but, isn't it asking me to get from 1/3 Sec y to 1/ Root 9 - x to the power of 2 ,
Yes, but . . .
Also worth noting that .
5. (Original post by joostan)
Yes, but . . .
I understand, but I'm asking what is the question asking of me? Is it asking me to rearrrange DY/DX in terms of Y to in terms of X?
6. (Original post by SunDun111)
...
The question wants you to go from into dy/dx as a function of x using the fact that
7. (Original post by Zacken)
The question wants you to go from into dy/dx as a function of x using the fact that
Right thanks!
8. (Original post by SunDun111)
Right thanks!
Do you now understand Joostan's (excellent) advice and can apply it here?
9. (Original post by Zacken)
Do you know understand Joostan's (excellent) advice and can apply it here?
First time i've heard it but trying to,
10. (Original post by SunDun111)
First time i've heard it but trying to,
Got it?
11. (Original post by Zacken)
Got it?
Unforunatley not, i understand the concept and have done other questions like this just now, but this particular one I am struggling to re-arrange, I will ask my teacher when I go back on Monday
12. (Original post by SunDun111)
Unforunatley not, i understand the concept and have done other questions like this just now, but this particular one I am struggling to re-arrange, I will ask my teacher when I go back on Monday

since

Now you know that so and .

Plug this back into the centered equation and remember that .
13. (Original post by Zacken)

since

Now you know that so and .

Plug this back into the centered equation and remember that .
Thanks I got it right, quick question
i am solving the equation 1 - 2ln X I took the 2lnx to the other side, and E'd both sides so i got
E to the power of 1 = 2x
14. (Original post by SunDun111)
Thanks I got it right, quick question
i am solving the equation 1 - 2ln X I took the 2lnx to the other side, and E'd both sides so i got
E to the power of 1 = 2x
No you didn't.

It is not the case that .

It is the case that .
15. (Original post by Zacken)
No you didn't.

It is not the case that it is the case that .
I see where I've gone wrong thanks
16. (Original post by SunDun111)
I see where I've gone wrong thanks
No problem.
17. (Original post by Zacken)
No problem.
Sorry for all the questions, doing a lot of revision today

This question is the curve has the equation (x to the power of 2 - 4x +1)e to the minus x, Dy/DX it and find the points,

Dy/dx should be minus e to the minus x (x to the power of 2 - 4x +1) + e to the minus x (2x - 2) = 0 how would I solve this?
18. (Original post by SunDun111)
Sorry for all the questions, doing a lot of revision today

This question is the curve has the equation (x to the power of 2 - 4x +1)e to the minus x, Dy/DX it and find the points,

Dy/dx should be minus e to the minus x (x to the power of 2 - 4x +1) + e to the minus x (2x - 2) = 0 how would I solve this?

So (no solutions) or (two solutions).

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