Linear Algebra : Operations and Properties

Study concepts, example questions & explanations for Linear Algebra

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Example Questions

Example Question #11 : The Transpose

Possible Answers:

Correct answer:

Explanation:

Example Question #11 : The Transpose

Possible Answers:

Correct answer:

Explanation:

Example Question #11 : The Transpose

Possible Answers:

Correct answer:

Explanation:

Example Question #21 : The Transpose

Possible Answers:

Correct answer:

Explanation:

Example Question #22 : The Transpose

Possible Answers:

Correct answer:

Explanation:

Example Question #23 : The Transpose

True or false: The transpose of a matrix with six rows and seven columns has seven rows and six columns.

Possible Answers:

False

True

Correct answer:

True

Explanation:

The transposition of a matrix switches the rows and the columns, so the number of rows in the original matrix is equal to the number of columns in the transpose, and vice versa. Therefore, a matrix with six rows and seven columns has seven rows and six columns.

Example Question #24 : The Transpose

Which of the following is equal to ?

Possible Answers:

The transpose of  does not exist.

Correct answer:

Explanation:

The transpose of a matrix switches the rows and the columns. Therefore, the first column of  has the same entries, in order, as the first row of , and so forth. Since 

it follows that

Example Question #25 : The Transpose

Let  and  be any two matrices of the same dimensions. 

True or false:

It must hold that .

Possible Answers:

False

True

Correct answer:

True

Explanation:

The transpose of the sum of two matrices is indeed equal to the sum of their transposes. Let us look at the two-by-two case - this reasoning can be generalized.

 and 

The transpose of a matrix switches the rows and the columns. Therefore, the first column of  has the same entries, in order, as the first row of , and so forth. Therefore, 

 and 

Matrices are added term by term, so

, the transpose of the sum of the original matrices, can be found by first adding the matrices termwise:

Take the transpose of the sum:

Indeed, .

Example Question #21 : The Transpose

 is a three-by-three matrix with determinant 0.

True, false, or undetermined:  does not have a transpose.

Possible Answers:

False

True

Undetermined

Correct answer:

False

Explanation:

Every matrix has a transpose regardless of the value of its determinant; finding the transpose is a matter of repositioning the elements - a concept independent of determinant - so that its rows are the columns of the transpose, and vice versa.

Example Question #21 : The Transpose

 is a two-by-two matrix such that

Which of the following could  be?

Possible Answers:

Correct answer:

Explanation:

Since  is a two-by-two matrix, we will let

,

where , and  represent real values.

The transpose of a matrix switches the rows and the columns. Therefore, the first column of  has the same entries, in order, as the first row of , and so forth. Therefore,

 

and

Add two matrices termwise:

Since 

or, equivalently,

The following must hold:

or

 

,

or 

 

and 

,

or, equivalently,

.

Therefore, any matrix of the form

for some real  would make the statement correct. The only choice matching this pattern is the matrix

.

 

 

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