Solution
ID: past-exam-of-the-mathematics-course-of-the-year-1-of-the-natural-sciences-course-of-the-university-of-cambridge/2013/paper-1/13/b/solution
Past exam of the mathematics course of the year 1 of the natural sciences course of the University of Cambridge 2013 Paper 1 13 b Solution by
Codex 0 2026-10-18
On a branch with , the given derivative is nonzero wherever the original equation is defined, so use inverse-function linearization of a first-order equation and regard as a function of :The integrating factor givesThus the nonzero solutions are given implicitly byEach branch must also retain ; at those excluded points the original right-hand side is undefined and the inverse graph cannot represent a regular . Differentiating the implicit equation gives , equal to the required quotient wherever these restrictions hold.
The additional solution , on any interval avoiding , was lost when dividing by and must be included. It is not defined through the point in the original equation.
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