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Application of Matrices and Determinants Important Questions

12th Standard

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Mathematics

Time : 01:00:00 Hrs
Total Marks : 50

    Part - A

    10 x 1 = 10
  1. If \(\rho\) (A) ≠ \(\rho\) ([AIB]), then the system is _____________

    (a)

    consistent and has infinitely many solutions

    (b)

    consistent and has a unique solution

    (c)

    consistent

    (d)

    inconsistent

  2. If A = \(\left[ \begin{matrix} 3 & -3 & 4 \\ 2 & -3 & 4 \\ 0 & -1 & 1 \end{matrix} \right] \), then adj(adj A) is

    (a)

    \(\left[ \begin{matrix} 3 & -3 & 4 \\ 2 & -3 & 4 \\ 0 & -1 & 1 \end{matrix} \right] \)

    (b)

    \(\left[ \begin{matrix} 6 & -6 & 8 \\ 4 & -6 & 8 \\ 0 & -2 & 2 \end{matrix} \right] \)

    (c)

    \(\left[ \begin{matrix} -3 & 3 & -4 \\ -2 & 3 & -4 \\ 0 & 1 & -1 \end{matrix} \right] \)

    (d)

    \(\left[ \begin{matrix} 3 & -3 & 4 \\ 0 & -1 & 1 \\ 2 & -3 & 4 \end{matrix} \right] \)

  3. If A is a matrix of order m \(\times\) n, then \(\rho\) (A) is _________

    (a)

    m

    (b)

    n

    (c)

    ≤ min (m,n)

    (d)

    ≥ min (m,n)

  4. If A = [2 0 1] then the rank of AAT is ______

    (a)

    1

    (b)

    2

    (c)

    3

    (d)

    0

  5. The two lines are Parallel (non-coincident) then the solution is ___________

    (a)

    Consistent and Only two solutions

    (b)

    Consistent and infinite number of solutions

    (c)

    no solution

    (d)

    consistent and unique solution

  6. If A\(\left[ \begin{matrix} 1 & -2 \\ 1 & 4 \end{matrix} \right] =\left[ \begin{matrix} 6 & 0 \\ 0 & 6 \end{matrix} \right] \), then A = 

    (a)

    \(\left[ \begin{matrix} 1 & -2 \\ 1 & 4 \end{matrix} \right] \)

    (b)

    \(\left[ \begin{matrix} 1 & 2 \\ -1 & 4 \end{matrix} \right] \)

    (c)

    \(\left[ \begin{matrix} 4 & 2 \\ -1 & 1 \end{matrix} \right] \)

    (d)

    \(\left[ \begin{matrix} 4 & -1 \\ 2 & 1 \end{matrix} \right] \)

  7. If (AB)-1 = \(\left[ \begin{matrix} 12 & -17 \\ -19 & 27 \end{matrix} \right] \) and A-1 = \(\left[ \begin{matrix} 1 & -1 \\ -2 & 3 \end{matrix} \right] \), then B-1 = 

    (a)

    \(\left[ \begin{matrix} 2 & -5 \\ -3 & 8 \end{matrix} \right] \)

    (b)

    \(\left[ \begin{matrix} 8 & 5 \\ 3 & 2 \end{matrix} \right] \)

    (c)

    \(\left[ \begin{matrix} 3 & 1 \\ 2 & 1 \end{matrix} \right] \)

    (d)

    \(\left[ \begin{matrix} 8 & -5 \\ -3 & 2 \end{matrix} \right] \)

  8. Which of the following is not an elementary transformation?

    (a)

    Ri ↔️ Rj

    (b)

    Ri ⟶ 2Ri + Rj

    (c)

    Cj ⟶ Cj + Ci

    (d)

    Ri ⟶ Ri + Cj

  9. If |adj(adj A)| = |A|9, then the order of the square matrix A is

    (a)

    3

    (b)

    4

    (c)

    2

    (d)

    5

  10. The system of linear equations x + y + z = 2, 2x + y - z = 3, 3x + 2y + kz = has a unique solution if __________

    (a)

    k ≠ 0

    (b)

    -1 < k < 1

    (c)

    -2 < k < 2

    (d)

    k = 0

  11. Part -B

    5 x 2 = 10
  12. If A is symmetric, prove that then adj A is also symmetric.

  13. If A = \(\left[ \begin{matrix} a & b \\ c & d \end{matrix} \right] \) is non-singular, find A−1.

  14. Solve the system of equations by Rank method x + y = 5, 2x + y = 8

  15. Find the rank of the following matrices by minor method:
    \(\left[ \begin{matrix} 1 \\ 3 \end{matrix}\begin{matrix} -2 \\ -6 \end{matrix}\begin{matrix} -1 \\ -3 \end{matrix}\begin{matrix} 0 \\ 1 \end{matrix} \right] \)

  16. If A = \(\left[ \begin{matrix} 8 & -4 \\ -5 & 3 \end{matrix} \right] \), verify that A(adj A) = (adj A)A = |A|I2.

  17. Part - C

    5 x 3 = 15
  18. Find the rank of the following matrices by row reduction method:
    \(\left[ \begin{matrix} 1 \\ \begin{matrix} 3 \\ \begin{matrix} 1 \\ 1 \end{matrix} \end{matrix} \end{matrix}\begin{matrix} 2 \\ \begin{matrix} -1 \\ \begin{matrix} -2 \\ -1 \end{matrix} \end{matrix} \end{matrix}\begin{matrix} -1 \\ \begin{matrix} 2 \\ \begin{matrix} 3 \\ 1 \end{matrix} \end{matrix} \end{matrix} \right] \)

  19. Find adj(adj (A)) if adj A = \(\left[ \begin{matrix} 1 & 0 & 1 \\ 0 & 2 & 0 \\ -1 & 0 & 1 \end{matrix} \right] \).

  20. Solve the following system of linear equations by matrix inversion method :
    2x  −  y  =  8 ,   3x  +  2y  =  −2.

    1. Verify that (A-1)T = (AT)-1 for A =\(\left[ \begin{matrix} -2 & -3 \\ 5 & -6 \end{matrix} \right] \).

    2. Test for consistency of the following system of linear equations and if possible solve:
      4x − 2y + 6z = 8, x + y − 3z = −1, 15x − 3y + 9z = 21.

  21. Part - D

    3 x 5 = 15
  22. If F(\(\alpha\)) = \(\left[ \begin{matrix} \cos { \alpha } & 0 & \sin { \alpha } \\ 0 & 1 & 0 \\ -\sin { \alpha } & 0 & \cos { \alpha } \end{matrix} \right] \), show that [F(\(\alpha\))]-1 = F(-\(\alpha\)).

  23. Find the inverse of each of the following by Gauss-Jordan method:
    \(\left[ \begin{matrix} 1 & -1 & 0 \\ 1 & 0 & -1 \\ 6 & -2 & -3 \end{matrix} \right] \)

  24. In a T20 match, a team needed just 6 runs to win with 1 ball left to go in the last over. The last ball was bowled and the batsman at the crease hit it high up. The ball traversed along a path in a vertical plane and the equation of the path is y = ax2 + bx + c with respect to a xy-coordinate system in the vertical plane and the ball traversed through the points (10, 8), (20, 16) (40, 22) can you conclude that the team won the match?
    Justify your answer. (All distances are measured in metres and the meeting point of the plane of the path with the farthest boundary line is (70, 0).)

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