1Which equation defines an eigenvalue and a corresponding nonzero eigenvector of a matrix ?
Factorization based on eigenvalues
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
An eigenvector keeps its direction when multiplied by , while the eigenvalue gives the scaling factor.
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2If a square matrix is diagonalizable, which factorization can be used?
Factorization based on eigenvalues
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
For a diagonalizable matrix, contains eigenvectors and contains the corresponding eigenvalues.
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3In the eigenvalue factorization , what does the diagonal matrix contain?
Factorization based on eigenvalues
Easy
A.The eigenvectors of
B.The determinants of
C.The eigenvalues of
D.The singular values of
Correct Answer: The eigenvalues of
Explanation:
The diagonal entries of are the eigenvalues of .
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4Which equation is commonly used to find the eigenvalues of a square matrix ?
Factorization based on eigenvalues
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The roots of the characteristic equation are the eigenvalues of .
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5Which expression represents the singular value decomposition of a matrix ?
Singular value decomposition
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The standard singular value decomposition is .
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6In , where are the singular values of stored?
Singular value decomposition
Easy
A.On the diagonal of
B.In every entry of
C.On the diagonal of
D.On the diagonal of
Correct Answer: On the diagonal of
Explanation:
The nonnegative singular values are placed on the main diagonal of .
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7Which statement about the singular values of a real matrix is correct?
Singular value decomposition
Easy
A.They are always equal
B.They are always complex
C.They are always negative
D.They are always nonnegative
Correct Answer: They are always nonnegative
Explanation:
Singular values are defined as nonnegative square roots of eigenvalues of .
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8The columns of in the decomposition are called what?
Singular value decomposition
Easy
A.Characteristic vectors
B.Left singular vectors
C.Diagonal singular values
D.Right singular vectors
Correct Answer: Left singular vectors
Explanation:
The columns of are the left singular vectors, while the columns of are the right singular vectors.
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9What is a root of a nonlinear equation ?
Solution of nonlinear equations
Easy
A.A value where
B.A value where
C.A value where
D.A value where
Correct Answer: A value where
Explanation:
A root is a value of that makes the function equal to zero.
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10Which of the following is a nonlinear equation?
Solution of nonlinear equations
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The term makes nonlinear. The other equations are linear in .
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11What condition is normally required to begin the bisection method on an interval ?
Bisection method
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Opposite signs at the endpoints indicate that a continuous function has at least one root inside the interval.
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12How is the midpoint calculated in the bisection method?
Bisection method
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The bisection method divides the current interval into two equal parts using .
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13What happens to the interval containing the root after one bisection iteration?
Bisection method
Easy
A.Its length is doubled
B.Its length becomes zero
C.Its length is halved
D.Its length is unchanged
Correct Answer: Its length is halved
Explanation:
Each iteration keeps one half of the current interval, so the interval length is divided by two.
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14How many initial approximations are required to start the secant method?
Secant method
Easy
A.Four approximations
B.One approximation
C.Two approximations
D.Three approximations
Correct Answer: Two approximations
Explanation:
The secant method uses two previous approximations to estimate the next root approximation.
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15What does the secant method use instead of the exact derivative ?
Secant method
Easy
A.A midpoint value
B.A second derivative
C.A finite-difference slope
D.An integral value
Correct Answer: A finite-difference slope
Explanation:
The secant method approximates the derivative using the slope through two points on the function.
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16Which formula gives the next approximation in the secant method?
Secant method
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
This formula uses two consecutive approximations and their function values to estimate the next approximation.
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17Which formula is used in the Newton-Raphson method?
Newton-Raphson method
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Newton-Raphson updates the approximation using the function value divided by its derivative.
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18What additional function information is required by the Newton-Raphson method?
Newton-Raphson method
Easy
A.The first derivative
B.The maximum value of
C.The definite integral of
D.The inverse function
Correct Answer: The first derivative
Explanation:
Newton-Raphson requires both and its first derivative .
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19For , what is for use in the Newton-Raphson method?
Newton-Raphson method
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
The derivative of is because the derivative of the constant is zero.
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20For and initial approximation , what is the next Newton-Raphson approximation ?
Newton-Raphson method
Easy
A.
B.
C.
D.
Correct Answer:
Explanation:
Using , we get .
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21For the matrix , which pair of matrices gives a valid factorization ?
Factorization based on eigenvalues
Medium
A.,
B.,
C.,
D.,
Correct Answer: ,
Explanation:
The eigenvalues are and , with corresponding eigenvectors and . Placing these eigenvectors in gives .
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22A nonsingular matrix has eigenvalues and . What is ?
Factorization based on eigenvalues
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The determinant is the product of the eigenvalues, so . Therefore, .
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23A diagonalizable matrix has eigenvalues and . What happens to as ?
Factorization based on eigenvalues
Medium
A. approaches the zero matrix
B. alternates between two matrices
C. becomes unbounded in magnitude
D. approaches the identity matrix
Correct Answer: approaches the zero matrix
Explanation:
Since both eigenvalues have magnitude less than , their powers approach zero. From , it follows that approaches the zero matrix.
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24What are the singular values of , listed in descending order?
Singular value decomposition
Medium
A. and
B. and
C. and
D. and
Correct Answer: and
Explanation:
The singular values are the square roots of the eigenvalues of . Here, , so the singular values are and .
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25A matrix has rank . In its compact SVD , what are the dimensions of , , and , respectively?
Singular value decomposition
Medium
A., , and
B., , and
C., , and
D., , and
Correct Answer: , , and
Explanation:
For a rank- compact SVD of an matrix, the dimensions are , , and . Here, , , and .
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26A matrix has singular values , , and . What is the Frobenius-norm error of its best rank-one approximation?
Singular value decomposition
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The best rank-one approximation retains the largest singular value. Its Frobenius error is .
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27For and , what is the minimum-norm least-squares solution ?
Singular value decomposition
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The pseudoinverse is . Thus, , which is the minimum-norm least-squares solution.
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28For the fixed-point iteration , which local condition near a fixed point supports convergence?
Solution of nonlinear equations
Medium
A. near
B. near
C. near
D. near
Correct Answer: near
Explanation:
For , local convergence is supported when . Since , the relevant condition is .
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29For a nonlinear system , Newton's method computes a correction . Which linear system should be solved?
Solution of nonlinear equations
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Linearizing gives . Therefore, the correction satisfies .
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30The equation is combined with . Which point in the first quadrant solves this nonlinear system?
Solution of nonlinear equations
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
From , we have . Substitution gives , so the first-quadrant solution is .
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31For , bisection begins on . After evaluating the first midpoint, which interval should be used next?
Bisection method
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
The midpoint is , where . Since , the sign change occurs on .
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32An initial bisection interval has length . What is the minimum number of bisections needed to make the interval length at most ?
Bisection method
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
After bisections, the length is . The requirement gives , so the minimum is .
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33Which condition guarantees that a continuous function has at least one root in the interval ?
Bisection method
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
If is continuous and its endpoint values have opposite signs, the Intermediate Value Theorem guarantees at least one root in .
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34Starting with an interval of length , what is the interval length after exactly four bisection iterations?
Bisection method
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Each iteration halves the interval length. After four iterations, the length is .
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35Apply one secant-method update to using and . What is ?
Secant method
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Using gives .
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36Why is the secant method useful when the analytical derivative of is difficult to obtain?
Secant method
Medium
A.It approximates the derivative using two function values
B.It guarantees convergence from every initial pair
C.It requires only the sign of each function value
D.It replaces the function by a constant approximation
Correct Answer: It approximates the derivative using two function values
Explanation:
The secant method replaces the derivative in Newton's method with a finite-difference slope computed from the two most recent iterates.
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37In the secant update, what is the main numerical concern when and are nearly equal?
Secant method
Medium
A.The update denominator becomes very small
B.The two iterates become exact root bounds
C.The root automatically becomes a multiple root
D.The function becomes discontinuous at
Correct Answer: The update denominator becomes very small
Explanation:
The denominator is . If it is nearly zero, the next step can become excessively large and numerically unstable.
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38Newton-Raphson is used to approximate by solving . If , what is ?
Newton-Raphson method
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
Newton's update is .
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39For , why can Newton-Raphson not proceed directly from ?
Newton-Raphson method
Medium
A., causing division by zero
B., making the function discontinuous
C., so another root is required
D., causing a repeated iterate
Correct Answer: , causing division by zero
Explanation:
Newton's formula divides by . Since and , the first update is undefined.
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40The function has a root of multiplicity . Which modified Newton update restores faster convergence when the multiplicity is known?
Newton-Raphson method
Medium
A.
B.
C.
D.
Correct Answer:
Explanation:
For a root of known multiplicity , modified Newton iteration uses . Here, .
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41Let . Which statement correctly describes the possibility of diagonalizing over ?
Factorization based on eigenvalues
Hard
A. is diagonalizable because its only eigenvalue is positive
B. is not diagonalizable because its determinant is zero
C. is diagonalizable because every triangular matrix is diagonalizable
D. is not diagonalizable because its eigenspace has dimension
Correct Answer: is not diagonalizable because its eigenspace has dimension
Explanation:
The characteristic polynomial is , so is the only eigenvalue. Since has nullity , there is only one linearly independent eigenvector, which is insufficient for diagonalization.
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42A real symmetric matrix has eigenvalues , , and . Which factorization and definiteness classification are correct?
Factorization based on eigenvalues
Hard
A. and is positive definite
B. and is negative semidefinite
C. and is positive semidefinite
D. and is indefinite
Correct Answer: and is indefinite
Explanation:
A real symmetric matrix admits the orthogonal factorization . Because its eigenvalues include both positive and negative values, the quadratic form takes both signs, so is indefinite.
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43Suppose is diagonalizable and has distinct eigenvalues , , and . What is the minimal polynomial of ?
Factorization based on eigenvalues
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The polynomial maps the eigenvalues to , , and . Therefore, has distinct eigenvalues and , and its minimal polynomial is , which is not listed. Since the stated options are inconsistent, none is correct.
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44Let . What is the best rank-one approximation to in the Frobenius norm?
Singular value decomposition
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The singular values are and . By the Eckart--Young theorem, the best rank-one approximation retains the component associated with the largest singular value, giving the first matrix.
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45For , which expression gives the Moore--Penrose solution of when ?
Singular value decomposition
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The equations reduce to . The Moore--Penrose solution is the minimum-norm solution, which distributes the sum equally: .
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46A matrix has singular values , , and . Which conclusion is valid for solving using an SVD-based pseudoinverse?
Singular value decomposition
Hard
A.The condition number is infinite, and the matrix has no nonzero singular values
B.The nonzero-spectrum condition number is , and the null-space component is undetermined
C.The condition number is zero, and every solution is unique
D.The condition number is , and no least-squares solution exists
Correct Answer: The nonzero-spectrum condition number is , and the null-space component is undetermined
Explanation:
The ratio of the largest to smallest nonzero singular value is , not . Thus this option is numerically incorrect, and none of the listed choices is fully valid.
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47For the system , how many real solutions exist?
Solution of nonlinear equations
Hard
A.No real solutions
B.Exactly one real solution
C.Exactly two real solutions
D.Infinitely many real solutions
Correct Answer: Exactly two real solutions
Explanation:
The equation gives . Substitution into yields , so or .
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48For , which statement about the number of real roots is correct?
Solution of nonlinear equations
Hard
A.It has exactly two real roots because its derivative has two zeros
B.It has exactly three real roots because its local extrema have opposite signs
C.It has exactly one real root because its degree is odd
D.It has no real roots because
Correct Answer: It has exactly three real roots because its local extrema have opposite signs
Explanation:
The derivative is , so the extrema occur at . Since and , the graph crosses the axis three times.
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49Consider with domain excluding . A numerical method reports convergence to . What is the correct interpretation?
Solution of nonlinear equations
Hard
A. is a valid double root because the numerator vanishes twice
B.The function has infinitely many roots near
C.The reported point is excluded from the domain and is not a root
D. is a valid simple root of the original equation
Correct Answer: The reported point is excluded from the domain and is not a root
Explanation:
Although the expression simplifies to for , the original function is undefined at . Numerical convergence to a point outside the domain does not produce a valid solution.
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50A continuous function satisfies on . After bisection iterations, what is the maximum possible interval width containing a root?
Bisection method
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
Each bisection halves the current interval. Starting with width , after iterations the width is .
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51For , a bisection method is initialized on . What is the midpoint after three completed iterations if the endpoint-value sign test is used?
Bisection method
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The initial midpoint is , where , so the new interval is . Midpoints then give with negative value and with positive value, producing after three updates. Thus the next midpoint is , so the listed iteration convention is ambiguous and none is unambiguously correct.
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52Which additional condition is required for bisection to guarantee convergence to a zero rather than merely relying on a sign change?
Bisection method
Hard
A.The function must be continuous on the closed initial interval
B.The function must be strictly convex on the initial interval
C.The derivative must be positive throughout the interval
D.The function must be twice differentiable at every midpoint
Correct Answer: The function must be continuous on the closed initial interval
Explanation:
The intermediate value theorem requires continuity. Without it, a sign change may result from a discontinuity rather than a zero.
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53A root is bracketed in an interval of width . What is the smallest number of bisection iterations needed to guarantee an absolute midpoint error below ?
Bisection method
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The midpoint error is at most . Requiring gives , so and is the smallest integer under the standard interval-width convention.
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54For the secant iteration applied to with and , what is ?
Secant method
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The secant formula gives .
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55Assuming a simple root and suitable initial approximations, what is the asymptotic order of convergence of the secant method?
Secant method
Hard
A.Quadratic, with order
B.Cubic, with order
C.Superlinear, with order approximately
D.Linear, with order
Correct Answer: Superlinear, with order approximately
Explanation:
The secant method has order of convergence equal to the golden ratio, , assuming the root is simple and the iterates enter a suitable local region.
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56In a secant iteration, while . What occurs in the standard update?
Secant method
Hard
A.The denominator vanishes, so the update is undefined
B.The next iterate is the midpoint of the two current points
C.The next iterate is exactly the known root
D.The method automatically becomes equivalent to Newton's method
Correct Answer: The denominator vanishes, so the update is undefined
Explanation:
The secant slope contains the denominator . If this difference is zero, the secant line is horizontal and its x-intercept is undefined.
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57Newton's method is applied to with . What is the local convergence behavior of the unmodified iteration?
Newton-Raphson method
Hard
A.Cubic convergence to
B.Linear convergence with factor
C.Quadratic convergence to
D.Divergence for every initial point near
Correct Answer: Linear convergence with factor
Explanation:
Since , Newton's update is . Thus the convergence is linear with factor .
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58For , Newton's method started at produces which first two iterates?
Newton-Raphson method
Hard
A.,
B.,
C.,
D.,
Correct Answer: ,
Explanation:
Newton's formula is . At , and , giving . Since and , .
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59For , which initial value causes the Newton update to be undefined at the first step?
Newton-Raphson method
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
The derivative is . It vanishes at . Among the listed values, only makes the Newton denominator zero.
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60For the nonlinear system , what is the Newton correction at ?
Newton-Raphson method
Hard
A.
B.
C.
D.
Correct Answer:
Explanation:
At , and the Jacobian is . Solving gives .
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