Implicit differentition: inverse functions,can someone me with my working

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Homework Help Overview

The discussion revolves around finding the derivative of the equation 1 - (x * arcsin(x)) / √(1 - x^2). The original poster attempts to apply the quotient rule to differentiate the expression, while also expressing confusion about the simplification process and the expected form of the answer.

Discussion Character

  • Mathematical reasoning, Problem interpretation, Assumption checking

Approaches and Questions Raised

  • Participants discuss the application of the quotient rule and the simplification of terms. The original poster questions the relationship between certain terms in their derived expression and the expected result. Others suggest focusing on collecting and simplifying terms related to arcsin.

Discussion Status

Some participants have provided guidance on simplifying expressions, while the original poster has made progress in understanding their work. There is an ongoing exploration of how to correctly manipulate the terms to reach the expected answer, with no explicit consensus on the final form yet.

Contextual Notes

The original poster expresses confusion regarding the mention of implicit differentiation in the thread title, indicating a potential misalignment with the problem context.

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Homework Statement



I'm trying to solve the derivative of this equation: 1-(x*arcsin(x))/√(1-x^2 )
I've straight away disregarded the 1 as it will be 0 so I'm left with -(x*arcsin(x))/√(1-x^2 ).

The Attempt at a Solution



I've applied the quotient rule and labelled U= -x*arcsin(x) and V=√(1-x^2 )
I then got du/dx= (-x)/√(1-x^2 )-arcsin⁡(x) and dv/dx= -x/√(1-x^2 )

I then used the quotient rule:
[√(1-x^2 )*{(-x)/√(1-x^2 )-arcsin⁡(x)}]-[-x*arcsin(x)*-x/√(1-x^2 )] / [√(1-x^2 )]^2

which then simplified to: [-x - arcsin⁡(x)*√(1-x^2 ) - (x^2)*arcsinx/√(1-x^2 )] / (1-x^2)

I then multiplied top and bottom by √(1-x^2 ) and got:
[-x√(1-x^2 ) - arcsinx*(1-x^2 ) - x^2*arcsinx] / (1-x^2 )*√(1-x^2 )

Then I separated everything to be individual and simplified:
-x/(1-x^2) - arcsinx/√(1-x^2 ) - x^2*arcsinx/(1-x^2 )*√(1-x^2 )

the real answer is meant to look like:
-x/(1-x^2) -arcsinx/(1-x^2)^(3/2)

I'm getting the first term but with the second term mine has an x^2 which I don't want and also I'm not seeing a (1-x^2)^(3/2) coming up anytime soon.

It would be greatly appreciated if someone could look over my work for any mistakes and also if someone could point me in the direction to finish the equation.
Thanks for your help in advance.
 
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e_brock123 said:
Then I separated everything to be individual and simplified:
-x/(1-x^2) - arcsinx/√(1-x^2 ) - x^2*arcsinx/(1-x^2 )*√(1-x^2 )

the real answer is meant to look like:
-x/(1-x^2) -arcsinx/(1-x^2)^(3/2)

These are identical. Just collect and simplify the arcsin terms.
 


Ok I've cleared most of it up now but I have to ask one thing, how does - arcsin(x)*(1-x^2) - x^2*arcsin(x) = -arcsinx? I just don't understand the process of what's happening there.
 


Actually don't worry I spoke to soon, I missed a simple rule of expanding the brackets. Thanks heaps for your help.
 


e_brock123 said:
Actually don't worry I spoke to soon, I missed a simple rule of expanding the brackets. Thanks heaps for your help.
Why does the title mention implicit differentiation ?
 

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