Solution

ID: past-exam-of-the-algebra-1-and-differential-equations-1-course-of-the-university-of-oxford/2014/4/b/iii/solution

Take any and any . Choose , so avoids zero. On
both and are continuous. They are bounded by compactness, and the bound on gives the uniform Lipschitz continuity in required by the Picard-Lindelöf theorem.
If is a bound for , shrink so and . Then the solution has , which supplies even strict inequalities at both edges of the requested vertical strip.
At , neither nor the original exponential expression is defined. Thus the theorem applies exactly for , with no restriction on . Failure of the hypotheses alone would not prove nonexistence; the explicit solutions below settle that issue.

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