Counting fifth-order partials in ten variables
Question
Let be a real-valued function on with continuous partial derivatives of every order, so mixed partials do not depend on the order of differentiation. How many distinct partial derivatives of order does have? (For instance, and each count as one.)
Short answer
. A fifth-order partial is determined by how many times each variable is differentiated, i.e. by a non-negative solution of . Stars and bars gives .
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Open the worked solutionLessons behind this question
- Counting and Combinatorics
- Sample Spaces, Events, and the Probability Axioms
- Conditional Probability, Total Probability, and Bayes' Rule
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