Inverse matrix

  • Thread starter Cafka
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  • #1
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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
 

Answers and Replies

  • #2
Hurkyl
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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.
 
  • #3
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Hurkyl said:
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.
 
  • #4
Hurkyl
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Then you can be confident in your answer!
 

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