Given the classical adjoint matrix and the determinant, how to find the inverse matrix?
Conditions
- A is a square matrix.
- .
- The classical adjoint matrix has been calculated.
Reasoning, step by step
- Verify that .
- Calculate the reciprocal of the determinant: .
- Multiply every entry of the adjugate matrix by this scalar value.
- The resulting matrix is the inverse matrix $.
Example
In the video, and . The inverse is calculated as .
Common misconceptions
- Forgetting to divide by the determinant and assuming the adjugate matrix is the inverse.
- Dividing the determinant by the adjugate matrix instead of the other way around.
- Applying the scalar multiplication incorrectly to only some entries of the adjugate matrix.
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