JEE Main20266 April 2026Evening ShiftMathematicsMatricesActual
Let A = bmatrix 1 & 0 & 0 3 & 1 & 0 9 & 3 & 1 bmatrix and B = [b_ ij ] , 1 i, j 3 . If B = A⁹⁹ - I , then the value of b₃₁ - b₂₁ b₃₂ is :
Options
- A99
- B199
- C149
- D159
Correct answer
C. 149
Step-by-step solution
Let A = I + C , where I is the identity matrix and C = bmatrix 0 & 0 & 0 3 & 0 & 0 9 & 3 & 0 bmatrix . Calculating the powers of C , we get: C^2 = bmatrix 0 & 0 & 0 3 & 0 & 0 9 & 3 & 0 bmatrix bmatrix 0 & 0 & 0 3 & 0 & 0 9 & 3 & 0 bmatrix = bmatrix 0 & 0 & 0 0 & 0 & 0 9 & 0 & 0 bmatrix C^3 = bmatrix 0 & 0 & 0 0 & 0 & 0 9 & 0 & 0 bmatrix bmatrix 0 & 0 & 0 3 & 0 & 0 9 & 3 & 0 bmatrix = bmatrix 0 & 0 & 0 0 & 0 & 0 0 & 0 & 0 bmatrix Since C^3 = 0 , all higher powers of C are also zero matrices. Using the binomial expan