If `A ,B ,A+I ,A+B` are idempotent matrices, then `A B` is equal to
If `A ,B ,A+I ,A+B`
are idempotent matrices, then `A B`
is equal to
A. `BA`
B. `-BA`
C. `I`
D. `O`
5 views
1 Answers
Correct Answer - B
Given `A, B, A + I, A+B` are idempotent. Hence,
`A^(2)=A, B^(2)=B, (A+I)^(2)=A+I` and `(A+B)^(2)=A+B`
`implies A^(2)+B^(2)+AB+BA=A+B`
`implies A+B+AB+BA=A+B`
`implies AB+BA=O`
5 views
Answered