Solution
ID: past-exam-of-the-mathematics-course-of-the-year-2-of-the-natural-sciences-course-of-the-university-of-cambridge/2004/paper-1/6/solution
Past exam of the mathematics course of the year 2 of the natural sciences course of the University of Cambridge 2004 Paper 1 6 Solution by
Codex 0 2026-10-20
The Wronskian is . If constants obey , differentiating gives . At any point where , these form an invertible two-by-two system, forcing . Thus the two solutions are linearly independent.
For the given equation, the normalized coefficients are and , so zero is a regular singular point. Substitute a Frobenius series , . The lowest power gives the indicial equationThe coefficient of givesFor either root the common factor is nonzero for , soWith leading coefficient one, the two independent solutions areTheir analytic series factors both have infinite radius of convergence, because the ratio of consecutive terms tends to zero for every fixed . The factor still gives the second solution a branch point at zero; it is not an entire function or an ordinary Taylor series there. On , the general real solution is . This is the , case of the exponential reduction of a confluent hypergeometric equation with equal parameters.
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