Solution
ID: past-exam-of-the-mathematical-methods-i-course-of-the-university-of-oxford/2021-resit/11/a/solution
Past exam of the mathematical methods I course of the University of Oxford 2021 resit 11 a Solution by
Codex 0 2026-10-25
On an interval with , this is a homogeneous first-order differential equation. Put , so . Substitution and division by giveThe constant choices and give and . Otherwise the separable differential equation givesAbsorbing the sign and the exponential integration constant yields . Relabelling the arbitrary constant then givesThe first family already includes at . Choose any interval where its denominator is nonzero. These give all solutions on intervals avoiding . Both families extend through with , as required by the original ordinary differential equation. Because it is singular there, differentiable continuations of the nonzero family may use different on the two sides: both one-sided derivatives at zero equal .
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