Linear Algebra : The Transpose

Study concepts, example questions & explanations for Linear Algebra

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Example Questions

Example Question #51 : Operations And Properties

Let , and  be real numbers such that 

,  ,

and the determinant of  is 8.

True or false: The determinant of  is 8.

Possible Answers:

False

True

Correct answer:

True

Explanation:

 is the transpose of  - the matrix formed by interchanging the rows of  with its columns. The determinant of a matrix and that of its transpose are equal, so, since  has determinant 8, so does .

Example Question #51 : Operations And Properties

Find .

Possible Answers:

Correct answer:

Explanation:

, the conjugate transpose of , is the result of transposing the matrix - interchanging rows with columns - and changing each entry to its complex conjugate. First, find transpose :

,

so

Change each entry to its complex conjugate:

.

Example Question #53 : Operations And Properties

Find .

Possible Answers:

None of the other choices gives the correct response.

Correct answer:

Explanation:

, the transpose, is the result of switching the rows of  with the columns. 

,

so

.

Example Question #31 : The Transpose

 and  are skew-symmetric matrices.

Which of the following is true of ?

Possible Answers:

Correct answer:

Explanation:

By definition, the transpose  of a skew-symmetric matrix  is equal to its additive inverse . It follows that

Example Question #55 : Operations And Properties

Find 

Possible Answers:

Correct answer:

Explanation:

, the conjugate transpose of , is the result of transposing the matrix - interchanging rows with columns - and changing each entry to its complex conjugate. First, find transpose :

,

so

Change each entry to its complex conjugate:

Example Question #56 : Operations And Properties

Which of the following is equal to  ?

Possible Answers:

None of the other responses gives the correct answer.

Correct answer:

Explanation:

, the conjugate transpose of , is the result of transposing the matrix - interchanging rows with columns - and changing each entry to its complex conjugate. First, find transpose :

Each entry of  is equal to the complex conjugate of the corresponding entry of . However, each entry in  is real, so each entry is equal to its own complex conjugate, and 

Example Question #56 : Operations And Properties

Find .

Possible Answers:

None of the other choices gives the correct response.

Correct answer:

Explanation:

, the transpose, is the result of switching the rows of  with the columns. 

,

so

.

Example Question #38 : The Transpose

Which of the following is equal to ?

Possible Answers:

Correct answer:

Explanation:

 is the transpose of  - the result of interchanging the rows of  with its columns.  is the conjugate transpose of  - the result of changing each entry of  to its complex conjugate. Therefore, if 

,

we can find  by simply changing each entry in  to its complex conjugate:

Example Question #32 : The Transpose

True or false:  is an upper triangular matrix.

Possible Answers:

False

True

Correct answer:

True

Explanation:

 is the result of interchanging rows of  with columns, then changing each entry to its complex conjugate. Also,  is equal to , so perform the same process on :

A matrix is upper triangular if all elements below its main (upper-left corner to lower right corner) diagonal are equal to 0. These elements in  are displayed in red above. Since all of the lower-triangular elements of  are zeroes,  is upper triangular.

Example Question #32 : The Transpose

Determine .

Possible Answers:

is undefined.

Correct answer:

is undefined.

Explanation:

is a two-by-three matrix. It follows that its transpose, , the result of switching rows with columns, is a three-by-two matrix. Since and have different dimensions, is an undefined expression.

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