How to use clairaut's theorem with 3rd order partial derivatives

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SUMMARY

This discussion focuses on applying Clairaut's Theorem to demonstrate the equality of third-order partial derivatives under the condition of continuity. Specifically, it asserts that if the third-order partial derivatives of a function are continuous, then the relationships fxxy = fyxy = fyyz hold true. The theorem states that mixed partial derivatives are equal when they are continuous, which is crucial for validating the equality in the context of the given function f = (x^3)(y^2)(z).

PREREQUISITES
  • Understanding of Clairaut's Theorem and its implications for mixed partial derivatives.
  • Knowledge of third-order partial derivatives and their notation.
  • Familiarity with multivariable calculus concepts.
  • Ability to perform differentiation of polynomial functions.
NEXT STEPS
  • Study the proof of Clairaut's Theorem in detail.
  • Practice differentiating various functions to find third-order partial derivatives.
  • Explore counterexamples where continuity of derivatives fails.
  • Learn about the implications of mixed partial derivatives in higher dimensions.
USEFUL FOR

Students and educators in multivariable calculus, mathematicians focusing on differential equations, and anyone interested in the properties of partial derivatives and their applications in mathematical analysis.

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Homework Statement



Use Clairaut's Theorem to show that is the third order partial derivatives are continuous, then fxxy=fyxy=fyyz

Clairaut's Theorem being: fxy(a,b)=fyx(a.b)

Homework Equations



fxyy=d/dy(d2f/dydx)=d^3f/dy^2dx

The Attempt at a Solution



Tried to differentiate the second partial derivatives but it didn't work out.
 
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counter example

Try when f = (x^3)(y^2)(z). After differentiating, try (5,7,11).
 

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