Question about implicit function theorem

In summary, the conversation discussed solving for z in terms of x and y and differentiating the resulting equation. The implicit function theorem was mentioned as a way to find a function Z(x,y) that satisfies the equation. The process of finding the derivatives of the equation was also discussed, with the conclusion that the method used was correct.
  • #1
chy1013m1
15
0
if z was solved in terms of x, y, then when we differenciate d (dz/dx) / dx, are we treating z as a constant or still a function of x, y ?
 
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  • #2
Have a bit more precise notation!

Now, for the equation F(x,y,z)=0, the implicit function theorem states that under relatively mild conditions, there exists a function Z(x,y), so that F(x,y,Z(x,y))=0 holds IDENTICALLY in an open region about a solution of F(x,y,z)=0.

We may find the expression for dZ/dx and d(dZ/dx)/dx by differentiatiang our identity with respect to x.
 
  • #3
so if I was to differenciate d(dZ/dx) / dx for F(x, y, z) = e^z + (x - z) * y - 4 = 0

i'd do: dz/dx = - (dF/dx) / (dF/dz) = - y * (e^z - y)^-1

then d (dz/dx) / dx = y * (e^z-y)^-2 * e^z * (dz/dx)

is that correct ?
 
  • #4
Assuming your expressions for the derivatives are correct, then you are correct since your method is correct. :smile:
 

What is the implicit function theorem?

The implicit function theorem is a mathematical tool that allows for the calculation of derivatives of implicit functions. It states that under certain conditions, if a function is defined implicitly by an equation, its derivative can be calculated by differentiating both sides of the equation with respect to one of the variables.

What are the conditions for the implicit function theorem to hold?

The implicit function theorem holds if the equation defining the implicit function is continuously differentiable and satisfies a non-singularity condition, known as the rank condition. This condition ensures that the derivative of the implicit function can be uniquely determined.

What is the difference between the implicit function theorem and the inverse function theorem?

The implicit function theorem deals with functions defined implicitly by equations, while the inverse function theorem deals with functions defined explicitly by equations. In other words, the implicit function theorem allows for the calculation of derivatives of implicit functions, while the inverse function theorem allows for the calculation of derivatives of explicit functions.

How is the implicit function theorem used in practical applications?

The implicit function theorem has numerous applications in mathematics, physics, and engineering. It is commonly used in optimization problems, differential equations, and in the study of surfaces and curves. It is also used in economics to analyze production functions and in biology to model population growth.

Are there any limitations to the implicit function theorem?

While the implicit function theorem is a powerful tool, it does have its limitations. It only applies to functions that are defined implicitly by equations, and not all equations can be solved using this theorem. Additionally, the theorem only works under certain conditions, and if these conditions are not met, the theorem may not hold.

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