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Functions which permute the roots of an equation

Published online by Cambridge University Press:  22 September 2016

F. J. Budden*
Affiliation:
Royal Grammar School, Newcastle upon Tyne

Extract

An amusing exercise to give to a mathematical sixth form is:

If the roots of the equation

F1(x) ≡ x3 + x2 − 2x − 1 = 0 (1)

are α, β, γ, form the equation whose roots are α2 − 2, β2 − 2, γ2 − 2.

The usual methods used will be, either to find the coefficients of the new equation by forming the appropriate symmetric functions of α, β, γ; or else to eliminate x from the relation y = x2 – 2 and the given cubic equation.

Type
Research Article
Copyright
Copyright © Mathematical Association 1976

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