Solution

ID: past-exam-of-the-mathematics-course-of-the-year-1-of-the-natural-sciences-course-of-the-university-of-cambridge/2009/paper-1/17/b/solution

The product rule gives
Thus this is an exact differential, and its zero level differential means . The initial data set , giving
The displayed interval is the maximal connected real interval containing on which this finite-valued solution is defined.

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