Solution

ID: past-exam-of-the-mathematics-course-of-the-year-2-of-the-natural-sciences-course-of-the-university-of-cambridge/2023/paper-2/6/a/ii/solution

Use three components of the proposed isotropic tensor form. Since , one gets . Since , one gets . Finally gives . Hence contraction of two Levi-Civita symbols gives

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