SOLUTION: determine whether the matrix has an inverse. if an inverse matrix exists, find it. {{{(matrix(2,2,2,-1,1,0))}}}

Algebra ->  Matrices-and-determiminant -> SOLUTION: determine whether the matrix has an inverse. if an inverse matrix exists, find it. {{{(matrix(2,2,2,-1,1,0))}}}       Log On


   



Question 365789: determine whether the matrix has an inverse. if an inverse matrix exists, find it. %28matrix%282%2C2%2C2%2C-1%2C1%2C0%29%29

Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
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 %28matrix%282%2C2%2C2%2C-1%2C1%2C0%29%29

Here are those steps done with your matrix.

1. %282%29%280%29-%28-1%29%281%29+=+0%2B1=1

2. %28matrix%282%2C2%2C0%2C-1%2C1%2C2%29%29
 
3. %28matrix%282%2C2%2C0%2C1%2C-1%2C2%29%29

4. %28matrix%282%2C2%2C0%2F1%2C1%2F1%2C-1%2F1%2C2%2F1%29%29, simplifying,

The inverse matrix is:

%28matrix%282%2C2%2C0%2C1%2C-1%2C2%29%29



-------------------------------

Checking to see if it really is the inverse matrix:

Multiply the original matrix by it:


%28matrix%282%2C2%2C0%2C1%2C-1%2C2%29%29%28matrix%282%2C2%2C2%2C-1%2C1%2C0%29%29



%28matrix%282%2C2%2C0%2B1%2C0%2B0%2C-2%2B2%2C1%2B0%29%29

%28matrix%282%2C2%2C1%2C0%2C0%2C1%29%29

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

Edwin