Solution

ID: past-exam-of-the-short-options-course-of-the-university-of-oxford/2017/6/a/ii/solution

Multiply the Sturm-Liouville equation by and integrate. The endpoint values and integration by parts give
Since ,
Thus the multiplier equals the stationary value of at the extremal, as in stationary values of a quadratic functional with a quadratic constraint. It is also the corresponding Rayleigh quotient.

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