Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2024/ib/paper-3/9g/solution

Fix . The map is a linear functional, so the finite-dimensional Riesz representation theorem gives a unique vector such that
For scalars ,
Uniqueness gives
so is linear.
For , apply this result to
It produces a unique linear map satisfying
which proves existence and uniqueness of the adjoint.

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