COMEDK2025MathematicsIndefinite IntegrationActual
If A= [ array lll a & 0 & 0 0 & a & 0 0 & 0 & a array ] then | adj A|=
Options
- Aa^2
- Ba^6
- Ca^9
- Da²⁷
Correct answer
B. a^6
Step-by-step solution
The matrix A is a scalar matrix of order n=3 , given by A = aI , where I is the identity matrix of order 3 . The determinant of A is |A| = vmatrix a & 0 & 0 0 & a & 0 0 & 0 & a vmatrix = a^3 . The property of the adjoint of a matrix states that | adj A| = |A|^ n-1 , where n is the order of the square matrix A . Substituting n=3 and |A| = a^3 into the formula: | adj A| = (a^3)³⁻¹ = (a^3)^2 = a^6 . Answer: a^6