Solution

ID: past-exam-of-the-differential-equations-and-applications-course-of-the-university-of-oxford/2010/a/1/ii/b/solution

Linearity follows from linearity of differentiation and point evaluation. For a test function supported in a fixed compact set , its value and derivative vanish at any point outside . Therefore
This proves the continuity estimate with and for every . Thus the stated mapping is a distribution of order at most one, supported in . In particular, a sequence tending to zero in the test function topology has both and .

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