KVPY2010MathematicsMatrices
Let A denote the matrix ( array ll 0 & i i & 0 array ) , where i²=-1 , and let I denote the identity matrix ( array ll 1 & 0 0 & 1 array ) . Then I + A + A ²+ + A ²⁰¹⁰ is -
Options
- A( array ll 0 & 0 0 & 0 array )
- B( array ll 0 & i i & 0 array )
- C( array ll 1 & 1 i & 1 array )
- D( array cc -1 & 0 0 & -1 array )
Correct answer
C. ( array ll 1 & 1 i & 1 array )
Step-by-step solution
array l A = [ array ll 0 & i i & 0 array ] ; A ²= [ array cc -1 & 0 0 & -1 array ] ; A ³= [ array cc 0 & - i - i & 0 array ] ; I = [ array ll 1 & 0 0 & 1 array ] I + A + A ²+ A ³= [ array ll 0 & 0 0 & 0 array ] ; A ⁴= [ array ll 1 & 0 0 & 1 array ]= I I + A + A ²+ A ³+ A ²¹⁰ ( I + A + A ²+ A ³ )+ A ⁴ ( I + A + A ²+ A ³ )+ + A ²⁰⁰⁸ ( I + A + A ² ) = ( array ll 1 & i i & 1 array ) array