Verifying Solution for |1 -1| = P |-2 1|

[Cafka]

Can someone verify this:

|1 -1| = P
|-2 1|

|-1 -1| For P^-1, i got this.
|-2 -1|

|-1 -2| My solutions manual, says this is the answer.
|-1 -1|

My solutions manual has been wrong before. The way i got my answer was to put the identity matrix to the right of P and solve for the right side and get the left into the identity.

|1 -1|1 0| = P
|-2 1|0 1|

|1 0|-1 -1| = P^-1
|0 1|-2 -1|

Thanks

 

[Hurkyl]

A good way to check your work is to multiply the two matrices together (P, and what you get for P^-1) and check if you get the identity back.

If you do for your matrix and not that in the answer book, you can be confident you did it right.

 

[Cafka]

A good way to check your work is to multiply the two matrices together (P, and what you get for P^-1) and check if you get the identity back.

If you do for your matrix and not that in the answer book, you can be confident you did it right.

Yeah, i multiplied them back and they went ot the identity matrix.

 

[Hurkyl]

Then you can be confident in your answer!