To find the inverse of a 2x2 matrix:

1. Calculate the determinant by the rule:

upper left element times lower right element minus
upper right element times lower left element

2. Exchange the upper left and lower right elements.

3. Change the signs of the upper right and lower left elements.

4. Divide each element by the value of the determinant found
   in step 1.


Find the determinant of 

Here are those steps done with your matrix.

1. 

2. 
 
3. 

4. , simplifying,

The inverse matrix is:





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Checking to see if it really is the inverse matrix:

Multiply the original matrix by it:










which is the identity matrix, so the inverse is correct.

Edwin