Mathematics - Vectors and Matrices

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36. The solution(s) to the equations
2x + 3y = 1
x- y = 4
4x - y = a
will exist if a is equal to

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37. The system of simultaneous equations
x + 2y + z = 6
2x + y + 2z = 6
x + y + z = 5
has

  • Option : C
  • Explanation : Given equations are;

    x + 2y + z = 6;

    2x + y + 2z = 6;

    x + y + z = 5

    Given system can be written as

    Linear Algebra

    Applying row operation  

    Linear Algebra

    we get,

    Linear Algebra

    Linear Algebra

    we get,

    Linear Algebra

    Since rank of co-efficient matrix is 2 and rank of argument matrix is 3, which is not equal. Hence system has no solution.

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38. A= The inverse of A is The inverse of A is

  • Option : A
  • Explanation : Linear Algebra = 5[3 - 0] - 0[0 - 2] + 2[0 - 6] = 15 - 12 = 3 Linear Algebra Linear Algebra
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39. Eigen values of the matrix

 
-1 4
4 -1
 
are

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40. If            If then eigen values of the matrix, I+A+A2 ,where I denotes the identity matrix are  

,then eigen values of the matrix, I+A+A2 ,where I denotes the identity matrix are

  • Option : C
  • Explanation : Linear Algebra

    A + I is a triangular matrix. Since eigen values of a triangular matrix are is diagonal elements, 

    therefore eigen values of 

    Linear Algebra

    are 3, 7, 13.

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