Linear Algebra


Q31.

Consider a matrix A=uv^{T}\; where \; u=\begin{bmatrix} 1\\ 2 \end{bmatrix},v=\begin{bmatrix} 1\\ 1 \end{bmatrix} Note that v^{T} denotes the transpose of v. The largest eigenvalue of A is _____.
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Q32.

Let A and B be two nxn matrices over real numbers. Let rank(M) and det(M) denote the rank and determinant of a matrix M, respectively. Consider the following statements. I. rank(AB)=rank (A)rank (B) II. det(AB)=det(A)det(B) III. rank(A+B) \leq rank (A) + rank (B) IV. det(A+B) \leq det(A) + det(B) Which of the above statements are TRUE?
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Q33.

Let P=\begin{bmatrix} 1 & 1&-1 \\ 2&-3 & 4\\ 3 &-2 & 3 \end{bmatrix} and Q=\begin{bmatrix} -1 & -2&-1 \\ 6 & 12& 6\\ 5&10 & 5 \end{bmatrix} be two matrices. Then the rank of P +Q is _____________.
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Q34.

Let A be nxn real valued square symmetric matrix of rank 2 with \sum_{i=1}^{n}\sum_{j=1}^{n}A^{2}_{ij}=50. Consider the following statements. (I) One eigen value must be in [-5, 5] (II) The eigen value with the largest magnitude must be strictly greater than 5. Which of the above statements about eigen values of A is/are necessarily CORRECT?
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Q35.

Let c_{1}....c_{n} be scalars, not all zero, such that \sum_{i=1}^{n}c_{i}a_{i}=0 where a_{i} are column vectors in R^{n}. Consider the set of linear equations Ax = b where A=a_{1}....a_{n} and b=\sum_{i=1}^{n}a_{i}. The set of equations has
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Q36.

Consider a quadratic equation x^{2} -13x +36 = 0 with coefficients in a base b. The solutions of this equation in the same base b are x = 5 and x = 6. Then b = ___________.
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Q37.

Consider a matrix P whose only eigenvectors are the multiples of \begin{bmatrix} 1\\ 4 \end{bmatrix}. Consider the following statements. (I) P does not have an inverse (II) P has a repeated eigenvalue (III) P cannot be diagonalized Which one of the following options is correct?
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Q38.

Consider the systems,each consisting of m linear equations in n variables. I. If m \lt n, then all such systems have a solution II. If m \gt n, then none of these systems has a solution III. If m = n, then there exists a system which has a solution Which one of the following is CORRECT?
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Q39.

Suppose that the eigen values of matrix A are 1, 2, 4. The determinant of (A^{-1})^{T} is _________.
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Q40.

The larger of the two eigenvalues of the matrix \begin{bmatrix} 4 & 5\\ 2&1 \end{bmatrix} is _______.
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