The matrix has 2 rows and 3 columns, so its order is .
Incorrect! Try again.
2Which matrix is called a square matrix?
Review of matrices
Easy
A.A matrix with equal columns
B.A matrix with zero entries
C.A matrix with equal rows
D.A matrix with equal rows and columns
Correct Answer: A matrix with equal rows and columns
Explanation:
A square matrix has the same number of rows and columns.
Incorrect! Try again.
3What is the transpose of ?
Review of matrices
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The transpose changes rows into columns, giving .
Incorrect! Try again.
4Which operation is an elementary row operation?
Elementary operations of matrices
Easy
A.Multiplying rows together
B.Squaring every entry
C.Adding two columns
D.Interchanging two rows
Correct Answer: Interchanging two rows
Explanation:
Interchanging two rows is one of the three elementary row operations.
Incorrect! Try again.
5What happens when a row is multiplied by a nonzero scalar during an elementary row operation?
Elementary operations of matrices
Easy
A.The matrix becomes square
B.The row is scaled
C.The row is deleted
D.The columns are reversed
Correct Answer: The row is scaled
Explanation:
Multiplying every entry in a row by a nonzero scalar scales that row.
Incorrect! Try again.
6Which row operation replaces by ?
Elementary operations of matrices
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The notation directly states that the second row is replaced by itself plus three times the first row.
Incorrect! Try again.
7The rank of a matrix is the maximum number of linearly independent __.
Rank of a matrix
Easy
A.Rows or columns
B.Zero entries
C.Diagonal entries
D.Square submatrices
Correct Answer: Rows or columns
Explanation:
The rank equals the maximum number of linearly independent rows or, equivalently, columns.
Incorrect! Try again.
8What is the rank of the zero matrix?
Rank of a matrix
Easy
A.The number of rows
B.The number of columns
C.
D.
Correct Answer:
Explanation:
The zero matrix has no nonzero linearly independent rows or columns, so its rank is .
Incorrect! Try again.
9What is the rank of the identity matrix ?
Rank of a matrix
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The three rows of are linearly independent, so its rank is .
Incorrect! Try again.
10Two vectors are linearly dependent if one vector is a __ of the other.
Linear dependence and independence of vectors
Easy
A.Scalar multiple
B.Determinant
C.Inverse
D.Transpose
Correct Answer: Scalar multiple
Explanation:
Two vectors are dependent when one can be written as a scalar multiple of the other.
Incorrect! Try again.
11Which set of vectors is linearly dependent?
Linear dependence and independence of vectors
Easy
A. and
B. and
C. and
D. and
Correct Answer: and
Explanation:
The vector is , so the vectors are linearly dependent.
Incorrect! Try again.
12A set containing the zero vector is always:
Linear dependence and independence of vectors
Easy
A.An orthogonal set
B.Linearly independent
C.Linearly dependent
D.A basis
Correct Answer: Linearly dependent
Explanation:
The zero vector gives a nontrivial linear combination equal to zero, so the set is dependent.
Incorrect! Try again.
13A system of linear equations is consistent if it has:
Solution of linear system of equations
Easy
A.Exactly two solutions
B.No solution
C.Only negative solutions
D.At least one solution
Correct Answer: At least one solution
Explanation:
A consistent system has at least one solution, whether the solution is unique or not.
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14The augmented matrix of and is:
Solution of linear system of equations
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The coefficients form the first two columns, and the constants form the last column.
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15A homogeneous system of linear equations always has which solution?
Solution of linear system of equations
Easy
A.Only a positive solution
B.Only a unique nonzero solution
C.No solution
D.The zero solution
Correct Answer: The zero solution
Explanation:
A homogeneous system has all constants equal to zero, so setting every variable to zero always gives a solution.
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16For a square matrix , the inverse satisfies:
Inverse of matrices
Easy
A. always
B.
C.
D.
Correct Answer:
Explanation:
The product of a nonsingular matrix and its inverse is the identity matrix.
Incorrect! Try again.
17A square matrix has an inverse only if its determinant is:
Inverse of matrices
Easy
A.One only
B.Nonzero
C.Negative
D.Zero
Correct Answer: Nonzero
Explanation:
A square matrix is invertible precisely when its determinant is nonzero.
Incorrect! Try again.
18For an eigenvalue and eigenvector , which equation holds?
Eigenvalues and eigenvectors
Easy
A. for every
B.
C.
D.
Correct Answer:
Explanation:
An eigenvector is a nonzero vector whose transformation by changes only its scale.
Incorrect! Try again.
19The sum of the eigenvalues of a square matrix equals its:
Properties of eigenvalues
Easy
A.Determinant
B.Trace
C.Rank
D.Inverse
Correct Answer: Trace
Explanation:
The sum of the eigenvalues, counted with multiplicity, equals the trace of the matrix.
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20The product of the eigenvalues of a square matrix equals its:
Properties of eigenvalues
Easy
A.Rank
B.Trace
C.Determinant
D.Transpose
Correct Answer: Determinant
Explanation:
The product of the eigenvalues, counted with multiplicity, equals the determinant.
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21If and , what is ?
Review of matrices
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Using row-by-column multiplication gives .
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22A matrix is obtained from a square matrix by interchanging two rows, multiplying one row by , and then adding twice one row to another. If , what is ?
Elementary operations of matrices
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
A row interchange changes the determinant's sign, row scaling multiplies it by , and row addition does not change it. Thus .
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23What is the rank of ?
Rank of a matrix
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The third row is the sum of the first two rows, while the first two rows are independent. Therefore, the matrix has two independent rows and .
Incorrect! Try again.
24For what value of are the vectors , , and linearly dependent?
Linear dependence and independence of vectors
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The determinant formed using the vectors as columns is . Linear dependence requires this determinant to be zero, giving .
Incorrect! Try again.
25Solve the system , , and .
Solution of linear system of equations
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Eliminating gives and . Solving these equations yields , , and then .
Incorrect! Try again.
26For what value of does the system and have infinitely many solutions?
Solution of linear system of equations
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The second equation must be exactly twice the first equation. Multiplying by gives , so .
Incorrect! Try again.
27What is the inverse of ?
Inverse of matrices
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Since , the inverse is .
Incorrect! Try again.
28If and are invertible matrices of the same order, which expression equals ?
Inverse of matrices
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The order reverses when a product is inverted because . Hence .
Incorrect! Try again.
29What are the eigenvalues of ?
Eigenvalues and eigenvectors
Medium
A. and
B. and
C. and
D. and
Correct Answer: and
Explanation:
The characteristic equation is , which factors as .
Incorrect! Try again.
30Which vector is an eigenvector of corresponding to the eigenvalue ?
Eigenvalues and eigenvectors
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
For , gives , so . Thus is a corresponding eigenvector.
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31An invertible matrix has eigenvalues , , and . What is ?
Properties of eigenvalues
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The eigenvalues of are , , and . Their sum is .
Incorrect! Try again.
32If the eigenvalues of are , , and , what are the eigenvalues of ?
Properties of eigenvalues
Medium
A., , and
B., , and
C., , and
D., , and
Correct Answer: , , and
Explanation:
If is an eigenvalue of , then is an eigenvalue of . Applying this gives , , and .
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33Using the Cayley-Hamilton theorem, find for .
Cayley-Hamilton theorem
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The characteristic equation is . Multiplying by gives .
Incorrect! Try again.
34A matrix satisfies the characteristic equation . Which expression is equal to ?
Cayley-Hamilton theorem
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
From , multiply by to get . Substitution gives .
Incorrect! Try again.
35For what value of does the matrix have rank ?
Rank of a matrix
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The second row is twice the first. For rank , the third row must also equal the first row, which requires .
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36Given , , and , which relation is correct?
Linear dependence and independence of vectors
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Adding the first two vectors gives . Therefore, the three vectors are linearly dependent.
Incorrect! Try again.
37The reduced augmented matrix of a linear system is . Which is its general solution?
Solution of linear system of equations
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Let the free variable be . The first row gives , and the second gives , so and .
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38A matrix is obtained from a matrix by the column operations and . If , what is ?
Elementary operations of matrices
Medium
A.
B.It cannot be determined
C.
D.
Correct Answer:
Explanation:
Elementary column operations preserve the rank of a matrix. Therefore, .
Incorrect! Try again.
39If is a matrix and is a matrix, which statement about is correct?
Review of matrices
Medium
A. and has order
B. and has order
C. and has order
D. and has order
Correct Answer: and has order
Explanation:
The product has order , so its transpose has order . Also, the transpose of a product reverses the order: .
Incorrect! Try again.
40What are the eigenvalues, including algebraic multiplicities, of ?
Eigenvalues and eigenvectors
Medium
A. twice and once
B. once and twice
C. twice and once
D., , and once each
Correct Answer: twice and once
Explanation:
For a triangular matrix, the eigenvalues are its diagonal entries. Thus the eigenvalues are , , and .
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41Let be a square matrix satisfying . Which expression equals ?
Review of matrices
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Using , . Setting gives .
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42A matrix is obtained from a matrix by interchanging two rows, multiplying one column by , and adding five times one row to another. If , what is ?
Elementary operations of matrices
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The row interchange contributes , the column scaling contributes , and the row replacement contributes . Thus .
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43Suppose is obtained from an matrix using elementary row operations. Which statement is always true?
Elementary operations of matrices
Hard
A. and have the same row and column spaces, but their ranks need not be equal.
B. and have the same determinant and null space whenever .
C. and have the same null space and rank, but their column spaces need not be equal.
D. and have the same column space and rank, but their null spaces need not be equal.
Correct Answer: and have the same null space and rank, but their column spaces need not be equal.
Explanation:
Row operations give for an invertible matrix . Hence exactly when , and rank is preserved. Left multiplication can change the column space as a subspace of .
Incorrect! Try again.
44For which values of does the matrix have rank exactly ?
Rank of a matrix
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The determinant is , so rank can drop only at or . Direct inspection at both values gives a nonzero minor, so the rank is exactly .
Incorrect! Try again.
45Let be an matrix of rank . What is the rank of the block matrix
Rank of a matrix
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The equations are and . Their combined nullity is , so rank-nullity gives .
Incorrect! Try again.
46Consider , , , and . For which value of are these vectors linearly dependent?
Linear dependence and independence of vectors
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Solving yields . A nontrivial solution exists only for , when .
Incorrect! Try again.
47Let be a basis of a three-dimensional vector space , and let be linear with . Which statement about is correct?
Linear dependence and independence of vectors
Hard
A.Their relation space is , and their span has dimension .
B.Their relation space is , and their span has dimension .
C.They are linearly independent because is a basis of .
D.Their relation space is , and their span has dimension .
Correct Answer: Their relation space is , and their span has dimension .
Explanation:
A relation means . Thus is a multiple of , and rank-nullity gives rank .
Incorrect! Try again.
48For which pair does the system have infinitely many solutions?
Solution of linear system of equations
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
After replacing the second and third rows by and , their coefficient rows coincide only when . Their constants then agree only when , giving rank .
Incorrect! Try again.
49For an matrix , suppose has a solution for every and has at most one solution for each . Which condition must hold?
Solution of linear system of equations
Hard
A. and
B. and
C. and
D. and
Correct Answer: and
Explanation:
Existence for every requires rank , while uniqueness requires nullity zero and hence rank . Therefore .
Incorrect! Try again.
50Let and . What is the inverse of ?
Inverse of matrices
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Since , the rank-one inverse formula gives , which evaluates to the stated matrix.
Incorrect! Try again.
51Let , , and be invertible square matrices of the same order. Without assuming that and commute, which expression equals ?
Inverse of matrices
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Factor . Reversing the factors when taking the inverse gives .
Incorrect! Try again.
52Let , where and . Which description of the eigenvalues and eigenspaces of is correct?
Eigenvalues and eigenvectors
Hard
A.The eigenvalues are ; and span the eigenspace.
B.The eigenvalues are ; the coordinate vectors form corresponding eigenvectors.
C.The eigenvalues are ; spans the eigenspace and is the zero eigenspace.
D.The eigenvalues are ; spans the eigenspace and is the zero eigenspace.
Correct Answer: The eigenvalues are ; spans the eigenspace and is the zero eigenspace.
Explanation:
Since , is an eigenvector with eigenvalue . Also, exactly when , giving a two-dimensional zero eigenspace.
Incorrect! Try again.
53For which statement is correct?
Eigenvalues and eigenvectors
Hard
A.The eigenspace for has dimension , the minimal polynomial is , and is not diagonalizable.
B.The eigenspace for has dimension , the minimal polynomial is , and is diagonalizable.
C.The eigenspace for has dimension , the minimal polynomial is , and is diagonalizable.
D.The eigenspace for has dimension , the minimal polynomial is , and is diagonalizable.
Correct Answer: The eigenspace for has dimension , the minimal polynomial is , and is not diagonalizable.
Explanation:
The matrix is a single size- Jordan block. Thus its only eigenspace is , and the largest Jordan block forces the minimal polynomial .
Incorrect! Try again.
54A real matrix has trace and one eigenvalue . What are its remaining eigenvalues and determinant?
Properties of eigenvalues
Hard
A.The remaining eigenvalues are and , and the determinant is .
B.The remaining eigenvalues are and , and the determinant is .
C.The remaining eigenvalues are and , and the determinant is .
D.The remaining eigenvalues are and , and the determinant is .
Correct Answer: The remaining eigenvalues are and , and the determinant is .
Explanation:
Nonreal eigenvalues of a real matrix occur in conjugate pairs, so is also an eigenvalue. The trace then gives the third eigenvalue as , and the determinant is .
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55Let be a matrix and a matrix. If the eigenvalues of are and , including algebraic multiplicity, what are the eigenvalues of ?
Properties of eigenvalues
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The products and have the same nonzero eigenvalues with algebraic multiplicities. Since is , it has one additional zero eigenvalue.
Incorrect! Try again.
56An invertible matrix has eigenvalues , , and . What are the eigenvalues of ?
Properties of eigenvalues
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
For each eigenvalue of , the corresponding eigenvalue is . Evaluating this at , , and gives the listed values.
Incorrect! Try again.
57An invertible matrix has characteristic polynomial . What is ?
Properties of eigenvalues
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The eigenvalues of are the reciprocals of those of , including algebraic multiplicity. Hence .
Incorrect! Try again.
58Let Using the Cayley-Hamilton theorem, which matrix equals ?
Cayley-Hamilton theorem
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The characteristic polynomial is . Cayley-Hamilton gives , so .
Incorrect! Try again.
59A square matrix satisfies . Which expression equals ?
Cayley-Hamilton theorem
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Modulo , write . Substitution of gives and , so .
Incorrect! Try again.
60An invertible matrix has characteristic polynomial . Which expression for follows from the Cayley-Hamilton theorem?
Cayley-Hamilton theorem
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Cayley-Hamilton gives . Multiplying by and rearranging yields .
Incorrect! Try again.
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