Solved Problems for Chapter 7

Let . When doing cofactor expansion along the top row, we encounter three minor matrices. What are they?

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Find the following determinant by (a) expanding along the first row, (b) second column.

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Compute the determinant by co-factor expansion. Pick the easiest row or column to use.

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An operation is done to get from the first matrix to the second. Identify what was done and tell how it will affect the value of the determinant.

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An operation is done to get from the first matrix to the second. Identify what was done and tell how it will affect the value of the determinant.

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An operation is done to get from the first matrix to the second. Identify what was done and tell how it will affect the value of the determinant.

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An operation is done to get from the first matrix to the second. Identify what was done and tell how it will affect the value of the determinant.

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An operation is done to get from the first matrix to the second. Identify what was done and tell how it will affect the value of the determinant.

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Let be an matrix and suppose there are rows such that all rows are linear combinations of these rows. Show .

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Construct matrices and to illustrate the property that .

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An matrix is called nilpotent if for some positive integer, it follows If is a nilpotent matrix and is the smallest possible integer such that what are the possible values of ?

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A matrix is said to be orthogonal if Thus the inverse of an orthogonal matrix is just its transpose. What are the possible values of if is an orthogonal matrix?

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Let and be two matrices. We say that is similar to and write provided that there exists an invertible matrix such that Show that if then .

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Determine whether each statement is true or false. If true, provide a proof. If false, provide a counter example.
(a)
If any two columns of a square matrix are equal, then the determinant of the matrix equals zero.
(b)
If exists then
(c)
If is a real matrix, then
(d)
If for some then

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Let Determine whether the matrix has an inverse by finding whether the determinant is non-zero.

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Bibliography

Some of the problems come from the end of Chapter 3 of Ken Kuttler’s A First Course in Linear Algebra. (CC-BY)

Ken Kuttler, A First Course in Linear Algebra, Lyryx 2017, Open Edition, pp. 272–315.

2024-09-06 23:25:48