Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
COMEDK20269 May 2026Evening ShiftMathematicsMatricesActual

Matrix A = bmatrix 1 & 1 & 2 1 & -2 & 2 1 & 0 & -1 bmatrix , Given M₂₂ and A₃₂ are the minor and cofactor of the adjoint matrix of A respectively then the value of the expression M₂₂ + A₃₂ - |adj A| is:

Options

  1. A-117
  2. B-729
  3. C-99
  4. D-81

Correct answer

D. -81

Step-by-step solution

The given matrix is A = bmatrix 1 & 1 & 2 1 & -2 & 2 1 & 0 & -1 bmatrix . First, we find the determinant of matrix A : |A| = 1((-2)(-1) - (2)(0)) - 1((1)(-1) - (2)(1)) + 2((1)(0) - (-2)(1)) |A| = 1(2) - 1(-3) + 2(2) = 2 + 3 + 4 = 9 Using the property of the adjoint of a matrix, |adj A| = |A|^ n-1 . For a 3 3 matrix, n = 3 : |adj A| = |A|³⁻¹ = 9^2 = 81 Let B = adj A . We need to find the minor M₂₂ and cofactor A₃₂ of matrix B . Let C be the cofactor matrix of B . By definition, adj B = C^T , which implies C = (adj B

Practice Matrices on Quantrex Academy →

More from Matrices

Given A = bmatrix x & 1 & -2 bmatrix and B = bmatrix 1 & 2 & 3 4 & 5 & 6 7 & 8 & 9 bmatrix . If ABA^t = [-20] then the value of x is: 2026If the matrix M = bmatrix x+5 & a & -4 -2 & 0 & b c & 6 & y+1 bmatrix is a skew symmetric matrix, the value of the expression ab + c^2 - xy is: 2026If A and B are two square matrices of the same order such that AB = A and BA = B , then (A + B)^2 is equal to: 2026Given the matrices A = bmatrix 1 & 0 & 1 0 & 1 & 0 1 & 0 & 2 bmatrix and B = bmatrix 2 & 1 & 0 1 & 1 & 2 0 & 2 & 1 bmatrix , then the minor M₂₃ of the matrix (A B⁻¹)⁻¹ is: 2026Given A = pmatrix 1 & 2 2 & 3 pmatrix and f(x) = x^2 - 2x - 3 then f(A) is: 2026If the system of equations 2 x+p y+6 z=8, x+2 y+q z=5 and x+y+3 z=4 has infinitely many solutions, then p = 2025If x^a y^b=e^m, x^c y^d=e^n, ₁= | array ll m & b n & d array |, ₂= | array ll a & m c & n array |, ₃= | array ll a & b c & d array | , then the values of x and y are respectively ( 2025If A= [ array ccc -1 & x & -3 2 & 4 & z y & 5 & -6 array ] is a symmetric matrix and B= [ array ccc 0 & 2 & q p & 0 & -4 -3 & r & s array ] is a skew symmetric matrix, then |A|+|B| 2025 Full Matrices list All COMEDK PYQs