Question

2 -2 4
-1 3 4
1 -2 -3

how is the above 3*3 matrix a idempotent matrix.can anybody help me out because when i am multiplying by itself values are coming different

Answer 1

The element in the first row, third column should be negative.

This matrix is actually an example of an idempotent matrix on the wikipedia page.

Answer 2

thanks a lot