Linear Algebra : Operations and Properties

Study concepts, example questions & explanations for Linear Algebra

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Example Questions

Example Question #19 : Range And Null Space Of A Matrix

, the set of all continuous real-valued functions defined on , is a vector space under the usual rules of addition and scalar multiplication. 

Let  be the set of all functions of the form 

for some real 

True or false:  is a subspace of .

Possible Answers:

True

False

Correct answer:

True

Explanation:

A set  is a subspace of a vector space if and only if two conditions hold, both of which are tested here.

The first condition is closure under addition - that is:

If , then 

Let  as defined. Then for some ,

and

Then 

or 

or

. The first condition is met.

The second condition is closure under scalar multiplication - that is:

If  and  is a scalar, then 

Let  as defined. Then for some 

For any scalar ,

or

. The second condition is met. 

, as defined, is a subspace.

 

Example Question #12 : Range And Null Space Of A Matrix

If  is an  matrix, find

Possible Answers:

Correct answer:

Explanation:

Since a basis for the row space and the column space of a matrix have the same, number of vectors then their dimensions are the same, say .

By the rank-nullity theorem, we have , or same to say

.

.

Hence .

Finally, applying the rank-nullity theorem to the transpose of , we have

, or the same to say

.

 (The row space dimension of  is the same as its transpose.)

.

Adding all four of our findings together gives us

.

 

Example Question #311 : Operations And Properties

Calculate the determinant of matrix A where

Possible Answers:

-50

0

45

Not Possible 

10

Correct answer:

Not Possible 

Explanation:

The matrix must be square to calculate its determinant, therefore, it is not possible to calculate the determinant for this matrix.  

Example Question #312 : Operations And Properties

Calculate the determinant of matrix A where,

 

Possible Answers:

0

12

7

-7

17

Correct answer:

7

Explanation:

To calculate the determinant of a 2x2 matrix, we can use the equation 

Example Question #313 : Operations And Properties

Calculate the determinant of matrix A where, 

Possible Answers:

54

504

0

-504

-315

Correct answer:

504

Explanation:

To calculate the determinant of a 2x2 matrix, we can use the equation 

Example Question #314 : Operations And Properties

Calculate the determinant of matrix A where, 

Possible Answers:

16

15

0

-15

17

Correct answer:

16

Explanation:

To calculate the determinant of a 2x2 matrix, we can use the equation 

Example Question #5 : The Determinant

Calculate the determinant of matrix A where,

Possible Answers:

15

26

-26

0

-24

Correct answer:

-26

Explanation:

Calculating the determinant of a 3x3 matrix is more difficult than a 2x2 matrix.  To calculate the determinant of a 3x3 matrix, we use the following 

Example Question #6 : The Determinant

Calculate the determinant of matrix A where,

Possible Answers:

-49

49

0

50

-50

Correct answer:

-50

Explanation:

Calculating the determinant of a 3x3 matrix is more difficult than a 2x2 matrix.  To calculate the determinant of a 3x3 matrix, we use the following 

Example Question #5 : The Determinant

Calculate the determinant of .

Possible Answers:

Correct answer:

Explanation:

By definition,

,

therefore,

.

Example Question #6 : The Determinant

Calculate the determinant of 

Possible Answers:

Correct answer:

Explanation:

For simplicity, we will find the determinant by expanding along the second row.  Consider the following:

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