Solution

ID: past-exam-of-the-mathematical-methods-i-course-of-the-university-of-oxford/2021-resit/8/c/iii/solution

Yes. The old matrix is triangular, with determinant zero and trace . The upper-left two-by-two block of the new matrix has determinant zero, so the whole determinant remains zero. Its trace is
Thus
This verifies both change of basis invariants from part (b).

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