Unit 3: Linear Algebra - Practice Quiz

CSE333 — Combinatorial Studies-I 60 Questions
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1 What is the order of the matrix ?

matrices Easy
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2 Which matrix has all entries equal to zero?

matrices Easy
A. Scalar matrix
B. Identity matrix
C. Zero matrix
D. Diagonal matrix

3 What is the transpose of ?

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4 Which matrix is the identity matrix?

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5 What is the determinant of ?

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6 What is the determinant of the identity matrix ?

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7 If a square matrix has two identical rows, what is its determinant?

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8 A square matrix is invertible when which condition holds?

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9 Which ordered pair solves the system and ?

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10 What does a consistent system of linear equations have?

system of linear equations Easy
A. Only the zero solution
B. No possible solution
C. Exactly two solutions
D. At least one solution

11 Which matrix form represents the linear system ?

system of linear equations Easy
A. Variable vector times constant vector equals coefficient matrix
B. Constant matrix plus variable vector equals coefficient vector
C. Coefficient vector minus constant matrix equals variable matrix
D. Coefficient matrix times variable vector equals constant vector

12 If two equations represent the same straight line, how many solutions does the system have?

system of linear equations Easy
A. No solutions
B. Infinitely many solutions
C. Exactly two solutions
D. Exactly one solution

13 If for a nonzero vector , what is called?

eigenvalues Easy
A. A transpose of
B. A determinant of
C. An inverse of
D. An eigenvalue of

14 What equation is used to find the eigenvalues of a square matrix ?

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15 What are the eigenvalues of the diagonal matrix ?

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A. and
B. and
C. and
D. and

16 Which vector cannot be an eigenvector?

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A. A unit vector
B. The zero vector
C. A nonzero vector
D. A column vector

17 For , which vector is an eigenvector corresponding to ?

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18 If is an eigenvector of with eigenvalue , which equality is true?

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19 In LU decomposition, a matrix is written in which form?

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20 In the factorization , what type of matrix is ?

LU decomposition Easy
A. Lower triangular matrix
B. Upper triangular matrix
C. Diagonal zero matrix
D. Symmetric identity matrix

21 Let and . What is ?

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22 If , what is ?

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23 Let and . What is the entry in row , column of ?

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24 Evaluate .

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25 Suppose . Matrix is obtained by interchanging two rows of and then multiplying one row by . What is ?

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26 For which values of is the matrix singular?

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27 If is a matrix with , what is ?

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28 Solve the system , , and .

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29 For what value of does the system and have infinitely many solutions?

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30 A system reduces to and , with free. Which expression describes its solution set?

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31 For which values of does the system and have a unique solution?

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32 What are the eigenvalues of ?

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33 Find the eigenvalues of .

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A. and
B. and
C. and
D. and

34 A matrix has eigenvalues , , and . What are the eigenvalues of ?

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35 Which vector is an eigenvector of corresponding to the eigenvalue ?

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36 Which vector is an eigenvector of corresponding to the eigenvalue ?

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37 For , which matrix diagonalizes as ?

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38 Using Doolittle's method, which is the LU decomposition of ?

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39 Suppose , where and . What is the solution of ?

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40 Using Gaussian elimination without row exchanges, what is the lower triangular factor in the LU decomposition of ?

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41 A real matrix satisfies and . What is ?

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C. The determinant cannot be determined because the matrix entries and eigenvectors are unspecified.
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42 Let be an invertible matrix with . If column vectors satisfy , find .

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43 For which values of and does the system

have no solution?

system of linear equations Hard
A. and
B. and
C. and
D. and

44 A matrix has characteristic polynomial and minimal polynomial . What is ?

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45 For which real values of does

admit an LU decomposition without row exchanges, with all diagonal entries of equal to ?

LU decomposition Hard
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C. , because only the second leading principal minor controls the existence of such a decomposition
D.

46 Evaluate

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47 For a real matrix , which statement about the matrix equation is correct?

matrices Hard
A. It has a unique solution whenever is invertible.
B. It is solvable precisely when is diagonalizable over the real numbers and has no repeated eigenvalues.
C. It has infinitely many solutions whenever has distinct eigenvalues.
D. It has no solution for any .

48 Consider , where
Which statement is correct?

system of linear equations Hard
A. For , the system has a unique solution.
B. For every , the system has infinitely many solutions.
C. For , the solution set has dimension .
D. For , the solution set has dimension .

49 Let be an invertible real matrix satisfying . Which value cannot equal ?

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50 Let . Which vector is an eigenvector of but not an eigenvector of ?

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51 Using Doolittle factorization , where has unit diagonal, let
What is the ordered pair ?

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52 Let be a real skew-symmetric matrix with . What is ?

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53 Let be a matrix of rank with and . If and is one solution of , what is the complete solution set?

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54 A matrix has eigenvalues , , and . Find

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55 Suppose is an complex matrix with distinct eigenvalues and . Which conclusion must hold?

eigenvectors Hard
A. Every eigenvector of is an eigenvector of .
B. must be a polynomial in of degree exactly , with a nonzero leading coefficient.
C. and must have exactly the same distinct eigenvalues.
D. Every eigenvector of is an eigenvector of .

56 If and are matrices with , what is the smallest possible value of ?

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57 For an arbitrary matrix , evaluate the block determinant

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58 Let be the tridiagonal matrix with every diagonal entry equal to and every entry immediately above or below the diagonal equal to . In the Doolittle factorization , what is ?

LU decomposition Hard
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59 Let be invertible and let nonzero vectors satisfy . For the system , which statement is correct?

system of linear equations Hard
A. It is solvable exactly when , and then it has a unique solution.
B. It is solvable exactly when , and then it has a one-parameter family of solutions.
C. It has a unique solution for every because adding a rank-one matrix to an invertible matrix preserves invertibility.
D. It is solvable exactly when , and then it has a one-parameter family of solutions.

60 A matrix satisfies , , and . What is the spectral radius of ?

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