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If A is a square matrix such that A^2=A ...

If `A` is a square matrix such that `A^2=A ,` then `(I+A)^3-7A` is equal to

A

A

B

I-A

C

I

D

3A

Text Solution

Verified by Experts

The correct Answer is:
A

`Given A^(2)=A`
`therefore (I+A)^(3)-7A=I^(3)+3I^(3)A +3IA^(2)+A^(3) -7A`
`=I+3A+3A^(2)+A^(3) -7A`
`=I+3A+3A +A.A^(2)-7A`
`=I-A+A.A`
`=I-A+A^(2)`
`=I-A+A=I`
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